JPH096616A - Method search method - Google Patents

Abstract

PURPOSE: To provide a high-speed method search method which reduces the calculation load for method search in a dynamic object-oriented system. CONSTITUTION: Method cache tables 204 to 206 are provided in objects 201 to 203 having succession relations, and names of methods which are started in the first operation by tracing and succeeding super objects and links to these methods are stored. When a message is received to start a method in second and following operations, method cache tables 204 to 206 are retrieved to acquire the cached link, and the method indicated by this link is started. Since information for first method search is held in objects 201 to 203 in this manner, the need for tracing the super objects is eliminated at the time of a second and following method search to reduce the calculation load for method search, and the method search speed is increased.

Description

Detailed Description of the Invention

[0001]

[Industrial application] Since it is impossible to calculate the address of a method in advance in a dynamic object-oriented system, the method to be used at the time of execution is searched and determined. The present invention relates to a method search method for executing a method inherited from a super object in such a dynamic object oriented system.

[0002]

2. Description of the Related Art First, a dynamic object-oriented system will be described.

Conventional general software is composed of data and a procedure describing a process. The procedure is described according to the content of the process, and the calculation is performed by passing the data as an argument to the procedure. On the other hand, the object-oriented system is characterized in that a procedure is described according to the type of data, and the system automatically determines the optimum procedure according to the data type of the argument when the procedure is called. This procedure is called a method, and the combination of data and method is called an object.

An area for holding some data inside an object is called a slot. The slot is realized as a pointer in the memory of the computer. For example, a slot storing an array is actually realized as a pointer to the array, and the reference to the slot is made via the pointer. Similarly, methods are implemented as pointers to procedures.

Objects communicate with each other using messages. Messages are used to convey all information such as calculation requests and replies. The message consists of a sequence of request types and parameters of arbitrary length. The object receiving the message determines the method to be executed according to the data type of the parameter and executes the corresponding method.

In programming, if you make a module that is mostly the same but only different,
In the past, after copying the original module, a new name was given and changes were made to accommodate different parts. On the other hand, objects have a hierarchical structure, and any object can use the slots and methods defined in the upper hierarchy. This is called inheritance.

The inheritance hierarchical structure is implemented as a pointer from an object to an object in the next higher hierarchy, and the objects are implemented as nodes. A tree-like or network-like inheritance structure is realized by these pointers and nodes.

In the inheritance hierarchical structure, the upper hierarchy object is called a super object, and the lower hierarchy object is called a sub object. In particular, the object one level above is called the direct super object, and the object one level below is called the direct sub-object.

In a static object-oriented system such as C _++, the addresses of methods and data are calculated in advance at the time of compiling, and the addresses are calculated at the time of executing the program. On the other hand, the dynamic object-oriented system determines the address of the method to be executed and the address of the data based on the message name and the data type of the parameter at the time of executing the program, and performs the calculation. This is called dynamic method invocation, and an object-oriented system having such characteristics is called a dynamic object-oriented system.

In a dynamic object-oriented system, when a message is received, the optimum method is determined and activated, but the intended method is not defined in the object that received the message, and inherited from the super object. It may be started by using. In this case, the target method is searched while following the pointer to the direct super object, and the found method is activated. A method search for a higher hierarchy of inheritance is called a method search.

As described above, in the system based on the object-oriented concept, the method is inherited from the parent object (super object). In a static object-oriented system (for example, C ₊₊ compiler), it is possible to calculate the address of a method that a super object has at the time of compilation, but in a dynamic object-oriented system (for example, Smalltalk).
Since it is impossible to calculate the method address in advance, the method to be used at the time of execution is searched and determined. The principle of this method search is shown in FIG.

In FIG. 9, 101, 102 and 103 are objects having an inheritance relationship, and SuperObj
The slot ect points to the parent super object. That is, the object (Ob
j_A) 101 is a super object of the object 102 (Obj_B) and the object 103 (Obj_C), and the object 102 is the object 10
3 is a super object. Object 101
, A method (Meth_A) 104 is defined by a slot called Methods, and the objects 102 and 103 have a method (Met_A).
h_A) 104 can be inherited and used.

Here, as shown at 105, the method M
A message message (Me
th_A) is sent to the object 103, the object 103 first sends its own M as shown at 106.
Searches for methods slots, but object 10
Since Meth_A is not defined in 3,
Using the rObject slot, the method slots 107 of the super object 102 are searched for. However, since the method Meth_A is not defined in the super object 102, the method Meth_A of the super object 101 is further defined as shown in 108.
Search for the odds slot. Super object 10
Since the method Meth_A is defined in 1, the search matches (match) and the corresponding method 104 can be activated.

[0014]

However, in the method execution by inheritance in the conventional dynamic object-oriented system as described above, the deeper the inheritance hierarchy, the more the method search calculation load increases. In particular, in a system such as an object-oriented database system in which each object is stored as data in an external storage device, I / O with the external storage device occurs because a super object on the external storage device is searched during method search. , Method search backwards in the inheritance hierarchy puts a heavy load on the system. Further, particularly in the case of a multi-user system, an object on the method search path, for example, in FIG. 9, when the object 102 is used by another person, the object 102 is locked and the object 102 is released. The request for the method search from the object 103 is kept waiting until the start, and the execution efficiency may be significantly reduced, or the execution may be impossible due to a timeout.

An object of the present invention is to provide a high-speed method search method that solves the above problems by reducing the calculation load on the method search.

[0016]

In order to achieve the above object, according to the invention of claim 1 of the present invention, in dynamic method execution in a dynamic object-oriented system, a method activated in the past in each object It has a cache area that stores names and links in association with each other, and when a message is sent to an object, the first step of searching the method corresponding to the message defined in the object, and the first step If a method corresponding to the message is defined and the method is activated and the process proceeds to the sixth step, and if the method corresponding to the message is not defined in the first step, in the object The link to the method corresponding to the message cached in the cache area of The third step, and in the third step, when the link to the method corresponding to the message is cached in the cache area, activates the method pointed to by the link and proceeds to the sixth step. And a fifth step of repeatedly applying the first to fifth steps for the super object of the object when the link to the method corresponding to the message is not cached in the cache area in the third step, The sixth step of associating the name of the invoked method with the link and caching in the cache area of the object to which the message was first sent, only when the method of the super object of the object to which the message was sent is inherited and used A method search method characterized by having and To.

Also, in the invention of claim 2 of the present invention, in addition to the above method, in the addition of the dynamic method in the dynamic object-oriented system, the first step of adding the method to the object of the method addition target. ,
The second step of searching for a link to the method having the same name as the method to be added, which is cached in the cache area in the object, and the link to the method having the same name as the method to be added in the second step is the object. And a third step of deleting the item with the corresponding link and name from the cache area when the object is cached in the cache area in the The method search method is characterized in that the method has a step of repeatedly applying the second step and the third step with respect to.

Further, in the invention of claim 3 of the present invention, in addition to the above method, in the dynamic method deletion in the dynamic object-oriented system, the method defined in the object whose method is to be deleted is deleted. The first step, the second step of searching for a link to the method with the same name as the method to be deleted, which is cached in the cache area in the object, and the link to the method to be deleted is the object in the second step. And a third step of deleting the item with the corresponding link and name from the cache area when the object has been cached in the cache area, and after executing the first step, the method deletion target object and all its sub-objects With a step of repeatedly applying a second step and a third step with respect to And means that method search method.

[0019]

According to the present invention, a cache area is provided in each object, the name of the method started first and the link to the method are stored in the cache area, and the cache area is searched when the method is started next time. By obtaining the cached link and activating the method pointed to by the obtained link, that is, by retaining the information of the method search performed in the past in each object, the calculation load on the method search To speed up method search. In the present invention,
The point that the method search while following the link of the super object is performed only for the first time is significantly different from the conventional technique that is performed every time.

[0020]

Embodiments of the present invention will be described below in detail with reference to the drawings.

<< Embodiment 1 >> First, a first embodiment of the present invention will be described. In this example, a method search according to the method described in claim 1 of the present invention will be schematically described. In this embodiment, a method of managing a method cache in a table will be described.

FIG. 1 is a diagram for explaining the initial method search according to the method of this embodiment. In FIG.
Objects 1, 202, and 203 have inheritance relations, and a slot called SuperObject points to a parent super-object, and a slot called SubObject points to a sub-object that becomes a child. That is, the object (Obj_A) 20
1 is a super object of the object (Obj_B) 202 and the object (Obj_C) 203, and the object 202 is a super object of the object 203. Supe of object 201
rObject slot and S of object 203
The ubObject slot is an empty link, indicating that there is no super object or sub object, respectively. Since the objects 201 to 203 each store and manage the method activated in the past, n
A method cache table (Methods Cash) having an ame field and a method field
e) Have 204-205. It is assumed that each of the objects 201 to 203 manages the method defined for each object by the Methods slot. That is, the object 201 has a method (Meth_
A) 207 is provided, and the object 202 and the object 203 can inherit and use the method 207.

As an example, the object 203 has a Meth
_A message that activates Message (Meth_
The case where A) is sent will be described with reference to FIG. 208
As shown in, the message Mess is sent to the object 203.
When “age (Meth_A)” is sent, the object 203 searches for its Methods slot, as indicated by 209. In this embodiment, the method called Meth_A is not defined in the object 203, so
Next, as shown in 210, the method cache table 2
Search in 06. Method cache table 206
Since the link to the method Meth_A is not cached, the method retrieves the Methods slot of the super object 202 as indicated by 211. Since the method called Meth_A is not defined in the super object 202, the method cache table 205 of the super object 202 is searched as shown in 212. Method cache table 2
Since the link to the method Meth_A is not cached in 05 as well, the Methods slot of the super object 201 is searched next as shown in 213. Since the method Meth_A 207 is defined in the super object 201, the search matches (match), and the corresponding method 207 is activated. At this time, as shown in FIG. 2 described later, the activated method name “Meth_A” is cached in the name field of the method cache table 206, and
The link to the activated method 207 is cached in the od field to establish the link as shown at 214.

FIG. 2 is a diagram for schematically explaining the method search from the second time onward by the method of this embodiment. When the same message Message (Meth_A) is sent to the object 203 after 208 shown in FIG. 1 (215), first, the object 203 searches its own Methods slot as shown in 216 as in the first time. In this embodiment, since the method called Meth_A is not defined in the object 203,
Next, as shown in 217, the method cache table 2
Search in 06. Since the link 214 to the method Meth_A is cached in the method cache table 206 as described above this time, the search matches (match) without tracing the super object as in the first time, and as shown in 218. Link 214
The 207 method Meth_A pointed to by can be immediately invoked.

<Embodiment 2> Next, a second embodiment of the present invention will be described. In this embodiment, a process at the time of adding a method by the method according to claim 2 of the present invention and a subsequent method search by the method according to claim 1 will be schematically described with reference to the drawings.

FIG. 3 is a diagram for explaining the method addition and the first method search after the method addition. As shown in FIG. 3, if a new method (Meth_A) 220 having the same name as the method 207 is added to the object 202, the message (Message (M
When the message eth_A) is sent, it is necessary to activate the method 220 instead of the method 207. This is called method overwriting. First,
Method 220 is defined on object 202 and Me
clear2 when added to the hods slot
The object 202 to which the method is added by 19 and all sub-objects (object 2 in this example)
03) cache table is searched, and the item of the link and the name of the method Meth_A that is cached is deleted (in this example, the method cache table 206
Delete the item).

After the method 220 is added, if a message Message (Meth_A) for invoking the method Meth_A is sent to the object 203 as shown by 221, first, as shown at 222, the object 2
Search the 03 Methods slot. Since the method called Meth_A is not defined in the object 203, the method cache table 206 is searched next as indicated by 223. Since the link to Meth_A is not cached in the method cache table 206 (deleted in the clear 219), the Methods slot of the super object 202 is searched as shown at 224. Since the method 220, Meth_A, is newly defined this time, the method 220 is activated. At this time, as shown in FIG. 4 described next, the activated method name “Meth_A” is cached in the name field of the method cache table 206, and the link to the method 220 activated this time is cached in the Method field. Then, a link as shown by 225 is established.

FIG. 4 shows the process after the method is added according to the present invention.
It is a figure which illustrates typically the method search after the 1st time. A message Mssag for invoking the method Meth_A on the object 203 after 221 shown in FIG.
When e (Meth_A) is sent (226), first,
As with the first time, the object 20 as shown at 227
3 searches his Methods slot. In this embodiment, since the method called Meth_A is not defined in the object 203, the method cache table 206 is searched as shown at 228. This time, as shown in FIG. 4, the method cache table 20
Since the link 225 to the method Meth_A is cached in 6, the search matches (match) as indicated by 229 and is pointed to by the link 225 without following the super object as in the first time 22
Method 0 Meth_A of 0 can be activated immediately.

<< Embodiment 3 >> Next, a third embodiment of the present invention will be described. In the present embodiment, a method for deleting a method by the method according to claim 3 of the present invention will be schematically described with reference to the drawings.

FIG. 5 is a diagram for explaining method deletion according to this embodiment. As shown by 230 in FIG. 5, when deleting the method 220 defined in the object 202 of FIG. 4, while deleting the method 220 defined in the Methods slot of the object 202, the method is deleted as shown in clear 231. The cache table of the object 202 to be deleted and all the sub-objects is searched by using the link to 220 as a key, and the corresponding item is deleted from the cache table (method cache tables 205 and 206 in this example).

<Embodiment 4> In the fourth embodiment, a method search and cache method according to the method described in claim 1 of the present invention will be described with reference to the flowchart of FIG.

Message (Met
If the message h_A) is sent then the method Meth_A must be invoked. When the message Message (Meth_A) is sent to the object O, the processing from 701 is performed.

First, the message Message (Met
The object O to which h_A) is sent is copied to the work area O1 (702). Next, the Meth of the work area O1
The odds slot is searched (703), and it is determined whether the method Meth_A is defined in the work area O1 (704). If the method Meth_A is defined in the Methods slot of the work area O1, the method Meth_A is activated (709) and the process proceeds to 712. If not defined, the process proceeds to 705. In 705, the method cache table Met of the work area O1
HodsCache is searched to determine whether the link to the method Meth_A is cached in the work area O1 (706). If it is cached, invoke the method Meth_A pointed to by the link (71
0) and proceed to 712. If not cached, proceed to 707. In 707, it is judged whether or not a super object exists in the work area O1, and if there is not, the method Meth_A cannot be found. Therefore, the method undefined error is processed (711) and the processing is terminated (714).
If there is a super object, proceed to 708. In 708, the super object of the work area O1 is redefined as the work area O1, and the process returns to 703. 709 or 7
When the method is activated in 10, the process proceeds to 712.

At 712, the object O and the work area O
If the object O and the work area O1 are the same object, the method Meth_A is defined in the object O to which the message Message (Meth_A) is sent, or the method Meth_A is determined. Since it indicates that the link to is already cached, the processing is terminated as it is (714), and if the object O and the work area O1 are not the same object, the process proceeds to 713, and the method cache table Me of the object O.
The method Meth_ that has been started in methodsCache
The link to A and the method name are stored (cached) and the processing is terminated (714).

<Fifth Embodiment> In the fifth embodiment, a method addition process according to the method of claim 2 of the present invention will be described with reference to the flowchart of FIG.

When the method Meth_A is added to the object O, the processing after 801 is performed. First, the method Me is added to the Methods slot of object O.
th_A is added (802). Next, the object O to which the method is added is copied to the work area O1 (803). Next, there is a possibility that a link to another method Meth_A is cached in the method cache table Methods Cache of the work area O1, so if there is such a link, the item of this link and name is deleted (804). Next, it is determined whether or not there is a sub-object in the work area O1 (805). If there is no sub-object, the process ends (807). If there is a sub-object, this is redefined as the work area O1 (8).
06), and return to 804.

<Embodiment 6> In the sixth embodiment, the method deletion processing by the method according to claim 3 of the present invention will be described with reference to the flowchart of FIG.

From object O to method Meth_A
In the case of deleting, the processing after 901 is performed. First,
The method Meth_A is deleted from the Methods slot of the object O (902). Next, the object O whose method has been deleted is copied to the work area O1 (903). Next, since there is a possibility that a link to another method Meth_A is cached in the method cache table Methods Cache of the work area O1, the item of this link and name is deleted (904). Next, it is judged whether or not there is a sub-object in the work area O1 (905). If there is no sub-object, the process ends (907). If there is a sub-object, this is redefined as the work area O1 (906), and the process returns to 904.

[0039]

As is apparent from the above description, the method search method according to claim 1 of the present invention caches a link to a method activated in the past in each object in a dynamic object-oriented system. , Since the method is started by using the link to the cached method at the subsequent method startup, there is no need to search the inheritance hierarchy for method search, and the calculation load is small and high-speed method startup is possible. There is. Especially in an object-oriented database that stores objects in an external storage device, I / O associated with method retrieval
It is expected that the speed will be significantly reduced due to a large decrease in the number of caches. Also, since the object has a cache, the cache will be persisted when the relevant object is persisted, and there will be no structural changes such as addition of methods. The effect of the cache lasts as long as possible. Also, since the method is invoked by bypassing the regular method search path, especially in an object-oriented database that is used by multiple users, object access conflict occurs even if another user is locking an object on the method search path. There is an effect that the method can be started immediately without the occurrence of.

The method search method according to claims 2 and 3 of the present invention has the same name as the method to be added or deleted when a dynamic method is added or deleted in the dynamic object-oriented system. Since the method and the link are deleted from the cache area of the object to be added or deleted and all the sub-objects, the method search method according to claim 1 is applied in conformity with the dynamic addition and deletion of the method. There is an effect that can be done.

[Brief description of drawings]

FIG. 1 is a diagram schematically illustrating a method search method according to a first embodiment of the present invention as a first embodiment of the present invention, and particularly a first method search.

FIG. 2 is a diagram schematically illustrating the method search method of the first embodiment, particularly the method search from the second time onward.

FIG. 3 relates to a method search method according to claim 2 of the present invention as a second embodiment of the present invention, and schematically shows a process at the time of dynamic method addition and a first method search after the method addition process. FIG.

FIG. 4 is a diagram schematically illustrating the method search method of the second embodiment, particularly the second and subsequent method searches after the method addition processing.

FIG. 5 is a diagram schematically illustrating a process at the time of dynamic method deletion as to a method search method according to claim 3 of the present invention as a third embodiment of the present invention.

FIG. 6 is a flowchart illustrating a method search method according to claim 1 of the present invention as a fourth embodiment of the present invention.

FIG. 7 is a flow chart for explaining a method addition method as a method search method according to a second embodiment of the present invention as a fifth embodiment of the present invention.

FIG. 8 is a flowchart illustrating a method search method according to claim 3 of the present invention as a sixth embodiment of the present invention, and illustrating a method deletion method.

FIG. 9 is a diagram schematically illustrating a method search method according to a conventional technique.

[Explanation of symbols]

201-203 ... Objects with inheritance relationship 204-206 ... Method cache table 207 ... Method 208 ... Message sent first time 214 ... Link 215 ... Message sent after second time 220 ... Added method 221 ... Method addition Message sent to the first time after 225 ... Link 226 ... Message sent after the second time after adding the method 230 ... Method deleted

Claims (3)

[Claims] 1. In dynamic method execution in a dynamic object-oriented system, each object has a cache area in which a name of a method activated in the past and a link are stored in association with each other, and a message is sent to the object. In this case, the first step of searching the method corresponding to the message defined in the object, and the sixth step by activating the method corresponding to the message defined in the first step Go to step 2 and search the link to the method corresponding to the message cached in the cache area of the object if the method corresponding to the message is not defined in the first step 3 And in the third step, the message is stored in the cache area. When the link to the method corresponding to is cached, the method corresponding to the message is activated in the cache area in the third step by activating the method pointed to by the link and proceeding to the sixth step. A fifth step in which steps 1 to 5 are repeatedly applied to the super object of the object when the link to is not cached, and the method of the super object of the object to which the message is sent is inherited and used A method search method characterized by having a sixth step of associating the name of the invoked method with a link and caching in the cache area of the object to which the message was first sent, only if 2. A dynamic object addition in a dynamic object-oriented system, the first step of adding a method to an object of a method addition target, and the addition target method cached in a cache area in the object. If the link to the method with the same name as the method to be added is cached in the cache area in the object in the second step of searching for a link to the method with the same name as And a third step of deleting the item from the cache area, and after the first step is executed, the second step and the third step are repeatedly applied to the object to which the method is added and all of its sub-objects. The method search method according to claim 1, wherein: 3. In dynamic method deletion in a dynamic object-oriented system, a first step of deleting a method defined in an object whose method is to be deleted, and cached in a cache area in the object, The second step of searching for a link to the method with the same name as the method to be deleted, and in the second step, if the link to the method to be deleted is cached in the cache area in the object, And a third step of deleting an item from the cache area, and after the first step is executed, the second step and the third step are repeatedly applied to the object for which the method is to be deleted and all of its sub-objects. The method search method according to claim 1, wherein the method search method is a method.