WO2017049488A1

WO2017049488A1 - Cache management method and apparatus

Info

Publication number: WO2017049488A1
Application number: PCT/CN2015/090416
Authority: WO
Inventors: 吴问付
Original assignee: 华为技术有限公司
Priority date: 2015-09-23
Filing date: 2015-09-23
Publication date: 2017-03-30
Also published as: CN108351873A; CN108351873B

Abstract

A cache management method and apparatus. By maintaining a record entry space of a fixed size and selectively eliminating stale record entries, the problem of waste of storage resources due to too many obsolete record entries is resolved. The method comprises: determining a first available space of a record entry space; and when the determined first available space does not satisfy a preset condition, deleting at least one stored record entry in the record entry space, the deleted at least one record entry having no corresponding content data in a data cache space.

Description

Cache management method and device

Technical field

The present invention relates to the field of communications technologies, and in particular, to a cache management method and apparatus.

Background technique

With the continuous improvement of the performance of mobile devices such as smart phones and tablets, more and more users choose to access the network anytime and anywhere through mobile devices. Among them, the number of people watching online videos through mobile devices is also increasing, and video data has become the main force of mobile network traffic. It is estimated that the global mobile data volume increases by 92% annually, and more than two-thirds of the data is video data.

The ever-increasing amount of mobile data has brought tremendous data transmission pressure to the Internet, and has led to a series of problems such as network congestion, server overload, long response time of user requests, and degraded network service quality. In order to cope with this challenge, the content distribution network (English: Content Delivery Network, CDN) technology came into being. In a traditional network, a user's request needs to reach the central server deployed by OTT (Over The Top) to get a response, as shown in Figure 1A. In the CDN, the user's request can be responded to at the CDN cache server at the "edge" of the network, as shown in Figure 1B. In this way, the user's request and the content data requested by the user can not pass through the central server, thereby greatly alleviating the pressure on the central server.

However, in the mobile network, after the content data requested by the user is obtained from the CDN cache server in the CDN, it still needs to pass through the core network of the operator (English: Core Network, referred to as CN) and the radio access network (English: Radio Access) Network, referred to as RAN, can reach the user equipment (English: User Equipment, referred to as UE), as shown in Figure 2. This brings a lot of traffic pressure to the operator's CN and RAN. A large number of concurrent requests can easily lead to network congestion and significantly increase network delay under limited network capacity.

In order to reduce the traffic pressure of the CN and the RAN, some content data may be buffered in the base station, and when the base station locally caches the content data requested by the user, it is directly returned to the user. The traditional cache management method generally divides the cache space of the base station into two parts when managing the content data buffered by the base station. As shown in FIG. 3, a part is a record item space for storing a record item, and the record item is used to describe access information of content data, such as the last access time, the total number of accesses, etc.; the other part is a data cache space, For storing cached content data. The total size of the record item space and the data cache space is fixed, but the respective sizes are not fixed. When adding a new record item, it is necessary to enlarge the record item space, and accordingly, the data cache space needs to be reduced.

After the access request for a certain content data arrives at the base station, the base station first determines whether the content data requested to be accessed has a corresponding record item in the record item space of the base station, and if so, updates its record item; otherwise, it records In the item space, a record entry is added for the content data requested to be accessed. Then, the base station determines whether the content data requested to be accessed exists in the data buffer space of the base station, and if so, directly returns the content data buffered in the data buffer space to the requester; otherwise, the content data is sent to the upper level of the base station. The request, such as the Public Data Network GateWay (English: Public Data Network GateWay, PGW for short), and the content data received from the upper level are sent to the requester.

Since the record items in the record item space can be used to track and record the access probability of the content data, the existing cache management method retains the record corresponding to the content data even when deleting the cached content data, which will This leads to the accumulation of many outdated entries, which wastes the limited storage resources of the base station.

Summary of the invention

The embodiment of the invention provides a cache management method and device, which are used to solve the problem that the obsolete record item wastes too much storage resources.

In a first aspect, an embodiment of the present invention provides a cache management method, including:

Determining the first available space of the record item space;

Deleting the stored at least one record item in the record item space when the determined first available space does not satisfy the set condition;

The deleted at least one record item does not have corresponding content data in the data cache space.

In conjunction with the first aspect, in a first possible implementation of the first aspect, determining that the entry is empty Before the first available space, it also includes:

Receiving an access request of the first device;

Determining that the content data requested by the access request does not have a corresponding record item in the record item space;

The setting condition is that at least one record item can be created, and after the stored at least one record item is deleted in the record item space, the method further includes:

In the record item space, a record item corresponding to the content data requested by the access request is created.

In conjunction with the first aspect, in a second possible implementation manner of the first aspect, before determining the first available space of the record item space, the method further includes:

Receiving an access request of the first device;

In the record item space, creating a record item corresponding to the content data requested by the access request;

The setting condition is that at least one record item can be created.

In conjunction with the second possible implementation of the first aspect, in a third possible implementation of the first aspect, in the record entry space, a record entry corresponding to the content data requested by the access request is created Previously, it also included:

Determining a second available space of the record item space;

It is determined that the second available space satisfies a set condition.

In conjunction with the first aspect and any one of the first to third possible implementations of the first aspect, in the fourth possible implementation of the first aspect, the deleted at least one record entry is The data cache space does not have a record item whose access probability is ranked in the last n bits in at least one record item of the corresponding content data.

With reference to the first aspect, and any one of the first to third possible implementation manners of the first aspect, in the fifth possible implementation manner of the first aspect, the deleted at least one record entry is The entry with the least probability of access is found in at least one record item in which the corresponding content data does not exist in the data cache space.

With reference to any one of the first to third possible implementation manners of the first aspect, in a sixth possible implementation manner of the first aspect, the content data stored in the data cache space is fixed in length Audio and video segments of value;

The method further includes:

If the audio and video segments requested by the access request are not stored in the data cache space, and the occupied space of the audio and video segments requested by the access request is larger than the available space of the data cache space, and the access Requesting, by the second device, the audio and video segment requested by the access request, and the use of the audio and video segment of the requested audio and video segment, and the access probability of the audio and video segment having the smallest access probability stored in the data buffer space The audio and video segments returned by the second device replace the audio and video segments stored in the data buffer space with the least probability of access.

With reference to any one of the first to third possible implementation manners of the first aspect, in a seventh possible implementation manner of the first aspect, the method further includes:

If the content data requested by the access request has a corresponding record item in the record item space, the record item corresponding to the content data requested by the access request is updated.

In conjunction with the seventh possible implementation of the first aspect, in an eighth possible implementation of the first aspect, the record entry includes the following fields:

Last access time, average access interval and number of visits; the average access interval is used to characterize the access probability;

Updating a record corresponding to the content data requested by the access request, including:

Updating a field included in the record item corresponding to the content data requested by the access request according to the access time included in the access request and the set forgetting factor;

The forgetting factor is updated periodically or irregularly according to the time-varying time when the device initiates the access request;

The time variation of the device initiating the access request satisfies the following conditions:

or

Where ΔP represents the time variation of the device initiating the access request, and P _t (i) represents the probability that the content data corresponding to the record of the access probability ranked in the ith bit in the record item space is requested at time _t , P _{t - δ} (i) represents the probability that the content data corresponding to the entry of the i-th bit in the record item space is requested at time t-δ, and M represents the record included in the record space The total number of N, N represents the total number of entries in the record item space in which the access probability ranks in the first N bits.

In conjunction with the eighth possible implementation of the first aspect, in a ninth possible implementation of the first aspect, the updated forgetting factor satisfies the following conditions:

a'=update _rate ×a+(1-update _rate )×ΔP;

Where a' indicates the updated forgetting factor, a indicates the forgetting factor before the update, and update _rate indicates the preset parameter, 0 <update _rate <1.

With reference to the first aspect and any one of the first to the ninth possible implementation manners of the first aspect, in the tenth possible implementation manner of the first aspect, the size of the recording item space is set according to Parameter RECORD _LIMIT setting;

The setting parameter RECORD _{LIMIT is} used to characterize a ratio of a maximum number of entries stored in the record space to a maximum number of content data stored in the data cache space; the setting parameter RECORD _{LIMIT is} greater than one.

With reference to the first aspect and any one of the first to tenth possible implementation manners of the first aspect, in the eleventh possible implementation manner of the first aspect, the record item in the record item space Stored in a minimal heap structure, the root node of the minimum heap is the record entry with the least probability of access in the record entry space.

In a second aspect, an embodiment of the present invention provides a cache management apparatus, including:

a processing module, configured to determine a first available space of the record item space; delete the stored at least one record item in the record item space when the determined first available space does not satisfy the set condition; The deleted at least one record item does not have corresponding content data in the data cache space.

In conjunction with the second aspect, in a first possible implementation of the second aspect, the device further includes:

a receiving module, configured to receive an access request of the first device before the processing module determines the first available space of the record item space;

The processing module is further configured to: after determining that the content data requested by the access request does not have a corresponding record item in the record item space, after deleting the stored at least one record item in the record item space, Creating a record item corresponding to the content data requested by the access request in the record item space; the setting condition is that at least one record item can be created.

In conjunction with the second aspect, in a second possible implementation of the second aspect, the device further includes:

The processing module is further configured to: if it is determined that the content data requested by the access request does not have a corresponding record item in the record item space, before determining the first available space of the record item space, in the record item space And creating a record item corresponding to the content data requested by the access request; the setting condition is that at least one record item can be created.

In conjunction with the second possible implementation of the second aspect, in a third possible implementation of the second aspect, the processing module is further configured to:

Determining a second available space of the record item space before creating a record item corresponding to the content data requested by the access request in the record item space; determining that the second available space satisfies a set condition.

With reference to the second aspect, and any one of the first to the third possible implementation manners of the second aspect, in the fourth possible implementation manner of the second aspect, the deleted at least one record item is The data cache space does not have a record item whose access probability is ranked in the last n bits in at least one record item of the corresponding content data.

Combining the second aspect with any one of the first to third possible implementations of the second aspect In a fifth possible implementation manner of the second aspect, the deleted at least one record item is a record item having the smallest access probability among the at least one record item in which the corresponding content data does not exist in the data cache space.

With reference to any one of the first to third possible implementation manners of the second aspect, in a sixth possible implementation manner of the second aspect, the content data stored in the data cache space is fixed in length Audio and video segments of value;

The processing module is further configured to:

With reference to any one of the first to third possible implementations of the second aspect, in a seventh possible implementation of the second aspect, the processing module is further configured to:

In conjunction with the seventh possible implementation of the second aspect, in an eighth possible implementation of the second aspect, the record entry includes the following fields:

When the processing module updates the record corresponding to the content data requested by the access request, the processing module is specifically configured to:

or

In conjunction with the eighth possible implementation of the second aspect, in a ninth possible implementation of the second aspect, the updated forgetting factor satisfies the following conditions:

a'=update _rate ×a+(1-update _rate )×ΔP;

With reference to the second aspect, and any one of the first to the ninth possible implementation manners of the second aspect, in the tenth possible implementation manner of the second aspect, the size of the recording item space is set according to Parameter RECORD _LIMIT setting;

With reference to the second aspect, and any one of the first to the tenth possible implementation manners of the second aspect, in the eleventh possible implementation manner of the second aspect, the record item in the record item space Stored in a minimal heap structure, the root node of the minimum heap is the record entry with the least probability of access in the record entry space.

With the solution provided by the embodiment of the present invention, by maintaining a fixed-size record item space, the old record items are selectively eliminated, thereby solving the problem that the obsolete record items waste too much storage resources.

DRAWINGS

1A is a schematic diagram of user response in a conventional network in the prior art;

FIG. 1B is a schematic diagram of user response in a CDN in the prior art; FIG.

2 is a schematic diagram of user response in a CDN based on a mobile network in the prior art;

3 is a schematic diagram of allocation of a record item space and a data cache space in the prior art;

FIG. 4 is a flowchart of a cache management method according to an embodiment of the present invention;

FIG. 5 is a schematic diagram of an access probability distribution of content data according to an embodiment of the present invention;

FIG. 6 is a schematic diagram of a video segment identifier according to an embodiment of the present disclosure;

FIG. 7 is a detailed flowchart of a base station management video buffer according to an embodiment of the present invention;

FIG. 8 is a schematic structural diagram of a cache management apparatus according to an embodiment of the present disclosure;

FIG. 9 is a schematic structural diagram of a cache management device according to an embodiment of the present invention.

detailed description

The present invention will be further described in detail with reference to the accompanying drawings, in which FIG. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present invention without creative efforts are within the scope of the present invention.

The embodiment of the invention provides a cache management method and device, which selectively eliminates stale entries by maintaining a fixed-size record item space, thereby solving the problem that the obsolete record items waste too much storage resources.

It should be understood that the technical solution of the embodiment of the present invention can be applied to a device with limited storage resources such as a base station and a PGW, and can also be applied to a device with rich storage resources such as a CDN cache server.

It should also be understood that the technical solution of the embodiments of the present invention can be used to manage various types of file caches, such as audio files, video files, image files, and the like.

FIG. 4 is a flowchart of implementing a cache management method according to an embodiment of the present invention, including:

Step 401: Determine a first available space of the record item space.

The available space is the space remaining in the current record item space except for the space occupied by the stored record items.

The total size of the record item space in the embodiment of the present invention is fixed, that is, the total number of record items that can be stored in the record item space is fixed, and does not increase continuously with the increase of the content data that appears.

Optionally, in the system initialization phase, the size of the record item space may be set according to the setting parameter RECORD _LIMIT , where the setting parameter RECORD _{LIMIT is} used to represent the maximum number of records items stored in the record item space and the data cache space. The ratio of the maximum number of stored content data; the set parameter RECORD _{LIMIT is} greater than one.

For example, the specification of a base station is to store a maximum of 10,000 videos. If the parameter RECORD _LIMIT is set to 2, it is considered that the space occupied by each entry generally does not exceed 1 kilobyte (unit: KB), so the record can be recorded. The size of the space is set to 20000KB.

Step 402: Delete at least one stored item in the record item space when the determined first available space does not satisfy the set condition; wherein the deleted at least one record item does not have a corresponding content in the data cache space data.

Optionally, the setting condition may be that at least one record item can be created; the so-called unsatisfied setting condition that the available space for characterizing the current record item space is insufficient to create at least one record item.

Optionally, the deleted at least one record item may be a record item whose access probability is ranked in the last n bits in at least one record item in which the corresponding content data does not exist in the data cache space; or the deleted at least A record item may be a record item with the least probability of access in at least one record item in which the corresponding content data does not exist in the data cache space.

The embodiment of the present invention can achieve the effect of being almost the same as storing all the recorded items by storing only a part of the recorded items, which is due to the concentrated characteristics of the device behavior. In practical applications, most of the device-initiated access requests are concentrated on a small amount of specific content data, while the rest of the content data has very few accesses. For systems with limited storage resources, generally only A portion of the content data with the highest probability of access is stored in the data cache space. For content data with low access probability, even if the system stores the records of the content data, the content data is unlikely to be cached in the system. Therefore, the embodiment of the present invention selects to discard the record items of the content data with low access probability, and selects the record items of the content data with high access probability, so that the storage resources can be saved, and the tracking content data can be obviously not affected. Access probability.

In the embodiment of the present invention, the method flow shown in FIG. 4 can have the following two trigger conditions:

Condition 1: According to the set period;

Condition 2: Unscheduled, such as receiving an access request of the first device, and determining that the content data requested by the access request does not have a corresponding record item in the record item space.

In the case of the above condition 2, before or after deleting at least one record item, it is necessary to create a record item corresponding to the content data requested by the access request in the record item space, which may be, but not limited to, the following: Three execution sequences:

Sequence one: first receiving an access request of the first device, and when determining that the content data requested by the access request does not have a corresponding record item in the record item space, performing step 401 and step 402, and then performing the record item In the space, a record item corresponding to the content data requested by the access request is created.

Sequence 2: first receiving an access request of the first device, and when determining that the content data requested by the access request does not have a corresponding record item in the record item space, creating and accessing the record item space The record corresponding to the requested content data is requested, and then steps 401 and 402 are performed.

Sequence 3: first receiving an access request of the first device, and determining that the content data requested by the access request does not have a corresponding record item in the record item space, determining a second available space of the record item, determining When the second available space satisfies the set condition, a record corresponding to the content data requested by the access request is created in the record item space, and then steps 401 and 402 are performed.

Optionally, if the content data requested by the access request has a corresponding record item in the record item space, the record item corresponding to the content data requested by the access request needs to be updated.

The Exponentially Weighted Moving-Average (EWMA) algorithm is an existing method for updating records.

In the EWMA algorithm, a record entry includes the following three fields: last access time, average access interval, and number of accesses; wherein the last access time and the average access interval are generally double-precision floating-point types (English: double) The variable, the number of accesses is generally an integer (English: int) variable; the average access interval is used to characterize the access probability.

When an access request is received, the access request generally carries an access time and an identifier of the requested content data, and the EWMA algorithm finds the record with the same identifier in the record item space according to the identifier of the content data requested by the access request. And then updating a field included in the record corresponding to the content data requested by the access request according to the access time included in the access request and the set forgetting factor;

Among them, the updated average access time interval meets the following conditions:

T'=(1-a)×T+a×(t _cur -t _last ) Formula (1)

The updated last access time meets the following conditions:

t _last '=t _cur formula (2)

The number of updated visits meets the following conditions:

Count'=Count+1 formula (3)

Where T' denotes the updated average access interval, T denotes the average access interval before the update, a denotes the forgetting factor, t _cur denotes the access time carried by the access request, t _last denotes the last access time before the update, t _Last ' indicates the last access time before the update, Count' indicates the number of accesses after the update, and Count indicates the number of accesses before the update.

The forgetting factor in the existing EWMA algorithm is a value between 0 and 1. By using the forgetting factor, on the one hand, the impact of the new access request on the "average access time interval" field can be reduced; on the other hand, The proportion of historical access requests in the "Average Access Interval" field can be reduced at a certain rate, which avoids the long-standing access request having too much impact on the current access probability.

When applying the EWMA algorithm to the management system cache, since different systems may face different device groups, the forgetting factors used by different systems should take different values. As the same system changes over time, the access behavior of the device group will also change, and the forgetting factor adopted should also change accordingly. However, since the existing EWMA algorithm cannot know in advance the time-varying size of the device-initiated access request, the setting of the forgetting factor becomes an important issue.

However, the embodiment of the present invention provides a method for adaptively adjusting the forgetting factor, which can dynamically adjust the forgetting factor by predicting the time variation of the access request initiated by the device. For example, when the time when the device initiates the access request is large, a larger forgetting factor is selected, and when the time when the device initiates the access request is small, a smaller forgetting factor is selected.

As shown in FIG. 5, it is a schematic diagram of an access probability distribution of content data, wherein the horizontal axis represents the ranking of the access probability of the content data corresponding to each record item in the record item space, for example, the access probability row in the record item space. The value of the content data corresponding to the record of the first bit on the horizontal axis is 1; the vertical axis represents the access probability; and the curve P _t represents the access probability distribution of the content data corresponding to each record item in the record entry space at time t. In the case, the curve P _t-δ represents the access probability distribution of the content data corresponding to each record item in the record item space at the time t-δ. Then, the amount of change in the device-initiated access request from the time t-δ to the time t can be expressed by the phase difference between the curve P _t and the curve P _t-δ , as shown by the dark portion in FIG. Assuming that the total number of entries included in the entry space is M, then the time variant of the device initiating the access request satisfies the following conditions:

Formula (4)

Where ΔP represents the time variation of the device initiating the access request, and P _t (i) represents the probability that the content data corresponding to the record of the ith bit in the record item space is requested at time _t , P _{t - δ} (i) indicates the probability that the content data corresponding to the record in which the popularity of the i-th bit ranks in the record item space is requested at time t-δ.

In addition, considering that the time-varying time when the device initiates the access request is mainly reflected in the change of the device requesting the access to the content data with high probability of access in different time periods, it is also possible not to accumulate the record. The access probability of the content data corresponding to each record item in the record space changes, but the access probability change of the content data corresponding to the record item whose access probability is ranked in the top N bits in the accumulated record space. In this case, the time-varying ΔP of the device initiating the access request satisfies the following conditions:

Formula (5)

Where N is the total number of entries in the record item space whose access probability is ranked in the first N bits. For the definition of the remaining parameters, refer to formula (4).

The forgetting factor is updated periodically or irregularly according to the time variation of the device initiated access request, and the updated forgetting factor satisfies the following conditions:

a'=update _rate ×a+(1-update _rate )×ΔP Equation (6)

Where a' denotes the updated forgetting factor, a denotes the forgetting factor before the update, update _rate denotes the preset parameter, 0<update _rate <1, and the value of ΔP can be referred to formula (4) or formula (5).

Equation (6) can be understood as smoothing the forgetting factor using a low pass filter, where update _rate can be understood as a filter parameter. Preferably, the update _rate can be taken as 0.4.

It should be noted that the technical means for setting the forgetting factor does not depend on the technical solution of the present invention, and is not limited to the scenario of managing the cache. The technical means may be implemented in cooperation with other technical means, or may be implemented separately.

Optionally, after receiving the access request of the first device, if the content data requested by the access request has a corresponding cache in the data cache space, the corresponding cache in the data cache space may be directly sent. Give the first device.

If the content data requested by the access request does not have a corresponding cache in the data cache space, the corresponding content data may be requested from the second device, and the content data returned by the second device is sent to the first device. The second device may be the same level device or a higher level device of the device that receives the access request, for example, the device that receives the access request is a base station, and the second device may be the same. Other base stations of the level may also be PGW or CDN cache servers of the upper level.

In addition, after receiving the content data returned by the second device, if the data cache If the available space of the space is not greater than the occupied space of the content data returned by the second device, the content data may be directly stored in the data cache space; if the available space of the data cache space is smaller than that returned by the second device For the occupied space of the content data, it is further determined whether the access probability of the content data is greater than the access probability of the content data having the smallest access probability in the data cache space. When it is determined that the access probability of the content data returned by the second device is not greater than the access probability of the content data with the smallest access probability, the content data returned by the second device may not be stored. When it is determined that the access probability of the content data returned by the second device is greater than the access probability of the content data with the smallest access probability, the content data with the smallest access probability may be deleted, if the data cache space after the deletion is sufficient for storing The content data returned by the second device is stored, and the content data returned by the second device is stored, otherwise the operation is repeated, and the content data with the lowest current access probability and the content returned by the second device are continuously compared. The access probability of the data, until a sufficient space is deleted in the data cache space for storing the content data returned by the second device, or access to the content data having the smallest current access probability in the data cache space is determined When the probability is greater than the content data returned by the second device, the content data returned by the second device is discarded.

Obviously, the above process of determining whether to cache the content data returned by the second device may waste more computing resources. In order to solve this problem, and considering that the content data requested by the access request is generally audio and video, the embodiment of the present invention proposes a method of performing equal length segmentation on audio and video.

In this method, the CDN cache server is responsible for equal length segmentation of each audio and video. The length of each audio and video segment is a fixed value, and different audio and video will be divided into different portions of audio and video segments. For example, if the fixed length of each audio and video segment is set to 1 minute, then the 10-minute video will be divided into 10 copies, and the 14-minute video will be divided into 14 copies. The CDN cache server is also responsible for marking the audio and video after these segments. Each audio segment has a unique identifier. The logo consists of two parts, one is the audio and video number, and the other is the segment number of the audio and video segment in the audio and video. For example, if the length of the video is 10 minutes and is divided into 10 video segments, the identifier of the fifth video segment is: {1:5}, as shown in FIG. 6.

The base station is responsible for converting the access request sent by the user equipment into a request for the audio and video segment. For example, When a user equipment requests the 5th to 6th minutes of the video No. 1, the predetermined length of each audio and video segment is 1 minute, the base station can convert the request of the user equipment into a pair of {1:5}. And the request for the audio and video segment identification of {1:6}.

In this way, between the base stations and the PGW and the CDN cache server, the audio and video segment identifiers can communicate with each other to determine the audio and video segments that need to be processed.

In this way, if the audio and video segments requested by the access request are not stored in the data cache space, and the occupied space of the audio and video segments requested by the access request is larger than the available space of the data cache space, The access probability of the audio and video segment requested by the access request is greater than the access probability of the audio and video segment having the smallest access probability stored in the data buffer space, and then the audio and video segment requested by the access request may be requested from the second device. And replacing the audio and video segments stored in the data buffer space with the least probability of access using the audio and video segments returned by the second device.

Since all the lengths of the audio and video segments are the same, when the cache is replaced, one-to-one replacement can be performed, that is, an audio and video segment can be cached to cache an audio and video segment, which is beneficial to reduce the calculation pressure. Moreover, since the access probability of different parts of the same audio and video is different in practical applications, for example, the user fast forwards or rewinds a video, which may cause a certain time period within the video with a high probability of access. The access probability is relatively low. Obviously, this part of the video segment with a small probability of access is not necessary to be cached in the system. However, if the audio and video segmentation is not performed, the complete video needs to be cached. Therefore, the audio and video segmentation can avoid the access probability. Small audio and video segments occupy the system's storage resources.

Optionally, in the embodiment of the present invention, the record item in the record item space may be stored in a minimum heap structure manner, and the root node of the minimum heap is the record item with the smallest access probability in the record item space. In this way, when determining whether to create a record item of the content data requested by the access request, the node may be taken from the top to the bottom of the root node of the minimum heap, if a node satisfies the corresponding record item in the data cache space. If there is no corresponding content data and the access probability of the record item is less than the access probability of the audio and video segment requested by the access request, the record corresponding to the node is replaced with the content data requested by the access request. Record item.

In order to more clearly illustrate the technical solution of the present invention, the following process is performed by an embodiment. It is to be understood that the following examples are merely one embodiment of the invention and are not intended to limit the invention.

As shown in FIG. 7, the method for managing a video buffer by a base station is as follows:

Step 701: The base station receives an access request of the user equipment.

Step 702: The base station determines identifiers of all video segments requested by the access request, and performs the following processing segment by segment.

Step 703: The base station determines whether the video segment requested by the access request has a corresponding record item in the record item space. If yes, step 704 is performed; otherwise, step 705 is performed.

Step 704: The base station updates the record corresponding to the video segment requested by the access request, and proceeds to step 708;

Step 705: The base station determines whether the record item space is sufficient to create a record item. If yes, step 707 is performed; otherwise, step 706 is performed.

Step 706: The base station searches for and deletes a record item having the smallest access probability among the records of the video in which the corresponding video does not exist in the record item stored in the record item space.

Step 707: The base station creates a record corresponding to the video requested by the access request in the record item space, and initializes each field included in the record item.

Step 708: The base station determines whether the video segment requested by the access request is stored in the data cache space. If yes, go to step 714; otherwise, go to step 709.

Step 709: The base station requests the video segment requested by the access request from the PGW cache server of the upper layer.

Step 710: The base station determines whether the data cache space is sufficient to store the video segment requested by the access request returned by the PGW cache server. If yes, go to step 713; otherwise, go to step 711.

Step 711: The base station determines whether the access probability of the video segment requested by the access request is greater than the access probability of the video segment with the smallest access probability stored in the data cache space. If yes, go to step 712; otherwise, go to step 714.

Step 712: The base station deletes a video segment that has the smallest access probability stored in the data cache space.

Step 713: The base station stores a video segment requested by the access request returned by the PGW cache server.

Step 714: The base station returns the video segment requested by the access request to the user equipment.

The cache management device and the cache management device provided by the embodiment of the present invention are described in detail below with reference to FIG. 8 and FIG.

FIG. 8 is a schematic structural diagram of a cache management apparatus 80 according to an embodiment of the present invention. As shown in FIG. 8, the apparatus 80 includes:

The processing module 801 is configured to determine a first available space of the record item space; when the determined first available space does not satisfy the set condition, delete the stored at least one record item in the record item space; wherein, at least one of the deleted items is deleted A record item does not have corresponding content data in the data cache space.

The device 80 further includes:

The receiving module 802 is configured to receive an access request of the first device before the processing module 801 determines the first available space of the record item space.

Optionally, based on the access request received by the receiving module 802, the processing module 801 may be further configured to: if it is determined that the content data requested by the access request does not have a corresponding record item in the record item space, then After deleting the stored at least one record item in the record item space, creating a record item corresponding to the content data requested by the access request in the record item space; the setting condition is that at least one record item can be created .

Alternatively, based on the access request received by the receiving module 802, the processing module 801 may be further configured to determine the record if it is determined that the content data requested by the access request does not have a corresponding record item in the record item space. Before the first available space of the item space, in the record item space, a record item corresponding to the content data requested by the access request is created; the setting condition is that at least one record item can be created.

Alternatively, based on the access request received by the receiving module 802, the processing module 801 may be further configured to: if it is determined that the content data requested by the access request does not exist in the record item space An entry record, determining a second available space of the record item space before determining the first available space of the record item space; and determining the second available space when the set condition is determined In the item space, a record item corresponding to the content data requested by the access request is created; the setting condition is that at least one record item can be created.

Optionally, the deleted at least one record item is a record item whose access probability is ranked in the last n bits in at least one record item in which the corresponding content data does not exist in the data cache space.

Optionally, the deleted at least one record item is a record item having the smallest access probability among the at least one record item in which the corresponding content data does not exist in the data cache space.

Optionally, if the content data stored in the data cache space is an audio/video segment with a fixed value, the processing module 801 is further configured to: if the audio and video segment requested by the access request is not stored in The occupied space of the audio and video segments requested by the access request is larger than the available space of the data cache space, and the access probability of the audio and video segments requested by the access request is greater than that stored in the data cache space. And an access probability of the audio and video segment having the smallest access probability in the data buffer space, requesting, by the second device, the audio and video segment requested by the access request, and replacing the audio and video segment returned by using the second device with the data. The audio and video segment with the least probability of access in the cache space.

Optionally, the processing module 801 is further configured to: if the content data requested by the access request has a corresponding record item in the record item space, update the record item corresponding to the content data requested by the access request .

Optionally, the record item includes the following fields: last access time, average access interval, and number of accesses; the average access interval is used to represent an access probability;

When the processing module 801 updates the record corresponding to the content data requested by the access request, the method is specifically configured to: update and request the access request according to the access time and the set forgetting factor included in the access request. The field included in the record item corresponding to the content data;

The forgetting factor is updated periodically or irregularly according to the time-varying time when the device initiates the access request; the device initiates the time-varying access request, and satisfies the following conditions:

or

Optionally, the updated forgetting factor satisfies the following conditions:

a'=update _rate ×a+(1-update _rate )×ΔP;

Optionally, the size of the record item space is set according to a setting parameter RECORD _LIMIT ; the setting parameter RECORD _{LIMIT is} used to represent the maximum number of records stored in the record item space and the content stored in the data cache space. The ratio of the maximum number of data; the set parameter RECORD _{LIMIT is} greater than one.

Optionally, the record items in the record item space are stored in a minimum heap structure, and the root node of the minimum heap is a record item having the smallest access probability in the record item space.

FIG. 9 is a schematic structural diagram of a cache management device 90 according to an embodiment of the present invention. As shown in FIG. 9, the device 90 includes:

Bus 901;

a processor 902 connected to the bus;

a memory 903 connected to the bus;

A transceiver 904 coupled to the bus.

The processor 902, by using the bus 901, invokes a program stored in the memory 903 for determining a first available space of a record item space; the first available space is determined to be dissatisfied When the condition is set, the stored at least one record item is deleted in the record item space; wherein the deleted at least one record item does not have corresponding content data in the data cache space.

The transceiver 904 is configured to complete the function of the receiving module 802 in the cache management device 80 under the control of the processor 902.

The processor 902 is further configured to complete the functions of the processing module 801 in the cache management device 80.

It should be understood that, in the embodiment of the present invention, the bus 901 may include a power bus, a control bus, a status signal bus, and the like in addition to the data bus. However, for the sake of clarity, the various buses are labeled as buses in the figure.

The processor 902 can be a central processing unit (English: Central Processing Unit, CPU for short), and can also be other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASICs), and ready-to-use programmable circuits. Gate array (abbreviation: FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components, etc. The general purpose processor may be a microprocessor or may be any conventional processor or the like.

Memory 903 can include read only memory and random access memory and provides instructions and data to processor 902. A portion of the memory 903 may also include a non-volatile random access memory.

The transceiver 904 can include a transmit circuit, a receive circuit, a power controller, a decoder, and an antenna.

In summary, the technical solution provided by the embodiment of the present invention maintains a fixed-size record item space that does not grow with time for storing a record item, and selectively selects an old record item according to the access probability included in the record item. Solved the problem that too many obsolete records are wasting storage resources.

Those skilled in the art will appreciate that embodiments of the present invention can be provided as a method, system, or computer program product. Accordingly, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment, or a combination of software and hardware. Moreover, the invention can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) including computer usable program code.

The present invention has been described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (system), and computer program products according to embodiments of the invention. It will be understood that each of the processes and/or blocks in the flowcharts and/or block diagrams, and the flows in the flowcharts and/or block diagrams can be implemented by computer program instructions. And/or a combination of boxes. These computer program instructions can be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing device to produce a machine for the execution of instructions for execution by a processor of a computer or other programmable data processing device. Means for implementing the functions specified in one or more of the flow or in a block or blocks of the flow chart.

The computer program instructions can also be stored in a computer readable memory that can direct a computer or other programmable data processing device to operate in a particular manner, such that the instructions stored in the computer readable memory produce an article of manufacture comprising the instruction device. The apparatus implements the functions specified in one or more blocks of a flow or a flow and/or block diagram of the flowchart.

These computer program instructions can also be loaded onto a computer or other programmable data processing device such that a series of operational steps are performed on a computer or other programmable device to produce computer-implemented processing for execution on a computer or other programmable device. The instructions provide steps for implementing the functions specified in one or more of the flow or in a block or blocks of a flow diagram.

Although the preferred embodiment of the invention has been described, it will be apparent to those skilled in the < Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and the modifications and

It is apparent that those skilled in the art can make various modifications and variations to the embodiments of the invention without departing from the spirit and scope of the embodiments of the invention. Thus, it is intended that the present invention cover the modifications and modifications of the embodiments of the invention.

Claims

A cache management method, comprising:

Determining the first available space of the record item space;

Deleting the stored at least one record item in the record item space when the determined first available space does not satisfy the set condition;

The deleted at least one record item does not have corresponding content data in the data cache space.
The method of claim 1, wherein before determining the first available space of the record item space, the method further comprises:

Receiving an access request of the first device;

Determining that the content data requested by the access request does not have a corresponding record item in the record item space;

The setting condition is that at least one record item can be created, and after the stored at least one record item is deleted in the record item space, the method further includes:

In the record item space, a record item corresponding to the content data requested by the access request is created.
The method of claim 1, wherein before determining the first available space of the record item space, the method further comprises:

Receiving an access request of the first device;

Determining that the content data requested by the access request does not have a corresponding record item in the record item space;

In the record item space, creating a record item corresponding to the content data requested by the access request;

The setting condition is that at least one record item can be created.
The method of claim 3, wherein before the creation of the entry corresponding to the content data requested by the access request in the record entry space, the method further comprises:

Determining a second available space of the record item space;

It is determined that the second available space satisfies a set condition.
The method according to any one of claims 1 to 4, wherein the deleted at least one record item is after the access probability is ranked in at least one record item in which the corresponding content data does not exist in the data cache space. N-bit record entry.
The method according to any one of claims 1 to 4, wherein the deleted at least one record item has a least probability of access in at least one record item in which the corresponding content data does not exist in the data buffer space. Record item.
The method according to any one of claims 2 to 4, wherein the content data stored in the data buffer space is an audio and video segment having a fixed length;

The method further includes:

If the audio and video segments requested by the access request are not stored in the data cache space, and the occupied space of the audio and video segments requested by the access request is larger than the available space of the data cache space, and the access Requesting, by the second device, the audio and video segment requested by the access request, and the use of the audio and video segment of the requested audio and video segment, and the access probability of the audio and video segment having the smallest access probability stored in the data buffer space The audio and video segments returned by the second device replace the audio and video segments stored in the data buffer space with the least probability of access.
The method of any of claims 2-4, wherein the method further comprises:

If the content data requested by the access request has a corresponding record item in the record item space, the record item corresponding to the content data requested by the access request is updated.
The method of claim 8 wherein said record entry comprises the following fields:

Last access time, average access interval and number of visits; the average access interval is used to characterize the access probability;

Updating a record corresponding to the content data requested by the access request, including:

Updating a field included in the record item corresponding to the content data requested by the access request according to the access time included in the access request and the set forgetting factor;

The forgetting factor is updated periodically or irregularly according to the time-varying time when the device initiates the access request;

The time variation of the device initiating the access request satisfies the following conditions:

or

Where ΔP represents the time variation of the device initiating the access request, and P t (i) represents the probability that the content data corresponding to the record of the access probability ranked in the ith bit in the record item space is requested at time t , P t - δ (i) represents the probability that the content data corresponding to the entry of the i-th bit in the record item space is requested at time t-δ, and M represents the record included in the record space The total number of N, N represents the total number of entries in the record item space in which the access probability ranks in the first N bits.
The method of claim 9 wherein the updated forgetting factor satisfies the following conditions:

a'=update rate ×a+(1-update rate )×ΔP;

Where a' indicates the updated forgetting factor, a indicates the forgetting factor before the update, and update rate indicates the preset parameter, 0 <update rate <1.
The method according to any one of claims 1 to 10, wherein the size of the record item space is set according to a setting parameter RECORD LIMIT ;

The setting parameter RECORD LIMIT is used to characterize a ratio of a maximum number of entries stored in the record space to a maximum number of content data stored in the data cache space; the setting parameter RECORD LIMIT is greater than one.
The method according to any one of claims 1 to 11, wherein the record items in the record item space are stored in a minimum heap structure, and the root node of the minimum heap is in the record item space The entry with the least probability of access.
A cache management device, comprising:

a processing module, configured to determine a first available space of the record item space; delete the stored at least one record item in the record item space when the determined first available space does not satisfy the set condition; wherein at least one of the deleted items The record item does not have corresponding content data in the data cache space.
The device of claim 13 wherein said device further comprises:

a receiving module, configured to receive an access request of the first device before the processing module determines the first available space of the record item space;

The processing module is further configured to: after determining that the content data requested by the access request does not have a corresponding record item in the record item space, after deleting the stored at least one record item in the record item space, Creating a record item corresponding to the content data requested by the access request in the record item space; the setting condition is that at least one record item can be created.
The device of claim 13 wherein said device further comprises:

a receiving module, configured to receive an access request of the first device before the processing module determines the first available space of the record item space;

The processing module is further configured to: if it is determined that the content data requested by the access request does not have a corresponding record item in the record item space, before determining the first available space of the record item space, in the record item space And creating a record item corresponding to the content data requested by the access request; the setting condition is that at least one record item can be created.
The device according to claim 15, wherein the processing module is further configured to:

Determining a second available space of the record item space before creating a record item corresponding to the content data requested by the access request in the record item space; determining that the second available space satisfies a set condition.
The apparatus according to any one of claims 13-16, wherein the deleted at least one record item is in an access probability after at least one record item in which the corresponding content data does not exist in the data cache space N-bit record entry.
The apparatus according to any one of claims 13 to 16, wherein the deleted at least one record item has a least probability of access in at least one record item in which the corresponding content data does not exist in the data buffer space. Record item.
The device according to any one of claims 14 to 16, wherein the content data stored in the data buffer space is an audio and video segment having a fixed length;

The processing module is further configured to:

If the audio and video segments requested by the access request are not stored in the data cache space, and the occupied space of the audio and video segments requested by the access request is larger than the available space of the data cache space, and the access Requesting, by the second device, the audio and video segment requested by the access request, and the use of the audio and video segment of the requested audio and video segment, and the access probability of the audio and video segment having the smallest access probability stored in the data buffer space The audio and video segments returned by the second device replace the audio and video segments stored in the data buffer space with the least probability of access.
The apparatus according to any one of claims 14-16, wherein the processing module is further configured to:

If the content data requested by the access request has a corresponding record item in the record item space, the record item corresponding to the content data requested by the access request is updated.
The apparatus of claim 20 wherein said entry comprises the following fields:

Last access time, average access interval and number of visits; the average access interval is used to characterize the access probability;

When the processing module updates the record corresponding to the content data requested by the access request, the processing module is specifically configured to:

Updating a field included in the record item corresponding to the content data requested by the access request according to the access time included in the access request and the set forgetting factor;

The forgetting factor is updated periodically or irregularly according to the time-varying time when the device initiates the access request;

The time variation of the device initiating the access request satisfies the following conditions:

or

Where ΔP represents the time variation of the device initiating the access request, and P t (i) represents the probability that the content data corresponding to the record of the access probability ranked in the ith bit in the record item space is requested at time t , P t - δ (i) represents the probability that the content data corresponding to the entry of the i-th bit in the record item space is requested at time t-δ, and M represents the record included in the record space The total number of N, N represents the total number of entries in the record item space in which the access probability ranks in the first N bits.
The apparatus according to claim 21, wherein the updated forgetting factor satisfies the following conditions:

a'=update rate ×a+(1-update rate )×ΔP;

Where a' indicates the updated forgetting factor, a indicates the forgetting factor before the update, and update rate indicates the preset parameter, 0 <update rate <1.
The apparatus according to any one of claims 13 to 22, wherein the size of the record item space is set according to a setting parameter RECORD LIMIT ;

The setting parameter RECORD LIMIT is used to characterize a ratio of a maximum number of entries stored in the record space to a maximum number of content data stored in the data cache space; the setting parameter RECORD LIMIT is greater than one.
The apparatus according to any one of claims 13 to 23, wherein the record items in the record item space are stored in a minimum heap structure, and the root node of the minimum heap is in the record item space The entry with the least probability of access.