Previous review

At the end of the last blog, we mentioned the two most important roles of client and server in the system framework , This blog , The workflow of the client will be parsed from the structure of the code , List of reference documents ：
distributedschedule_samgr_lite/samgr_client/source/remote_register.c

The relevant code comments and function introduction of this file are mentioned in the previous blog ：
OpenHarmony Module two samgr_client File header and source file parsing

Function introduction

Under the document , It is mainly divided into the following function modules , The functions they involve are also the functions we will analyze in depth ：

SAMGR_RegisterServiceApi	// Remote register service application programming interface 
SAMGR_FindServiceApi	// Find services Api
SAMGR_RegisterSystemCapabilityApi	// Register system capabilities Api
SAMGR_QuerySystemCapabilityApi	// Query system functions Api
SAMGR_GetSystemCapabilitiesApi	// Get system functions Api
ClearRegistry	// Clear registry 
InitializeRegistry	// Registry initialization 

You can see from the function , Basically, every service function cannot be built without initialization , The first step of initialization is to determine whether the registry needs to be cleared , So let's start with initialization , Start analyzing the process .

Initialization operation

ClearRegistry Clear registry

This clearing operation is mainly divided into three processes ：
① call VECTOR_Clear Function destroys vector objects
② call CloseLiteIpc Function off LiteIpc
③ call SAMGR_Free Function to free the free memory

Do the above , The data of the registry that originally contained the data has been cleared

InitializeRegistry Registry initialization

The initialization operation is mainly divided into two steps ：① Clear registry ;② Apply for a new space to fill in new data .

The first step to clear the registry is to use the above ClearRegistry function
The second step is divided into three steps ：

        g_remoteRegister.mtx = MUTEX_InitValue();   // Apply for a temporary space 
        g_remoteRegister.clients = VECTOR_Make((VECTOR_Key)SAMGR_GetSAName, (VECTOR_Compare)SAMGR_CompareSAName);// Create or initialize vector objects . 
        g_remoteRegister.endpoint = SAMGR_CreateEndpoint("ipc client", NULL); // Create a terminal 

Pay attention to the function of creating terminal ：SAMGR_CreateEndpoint
The function of this function is to create a terminal , The specific steps are as follows ：
① Apply for a temporary space （SAMGR_Malloc）
② open LiteIpc（OpenLiteIpc）
③ Create or initialize vector objects .（VECTOR_Make）

The text description seems a little convoluted , So I drew its flow chart for you to understand ：

Initialization is the most basic and important operation in the client , All services must be initialized first , Otherwise, it will cause data disorder , The remaining functions will be comprehensively analyzed in the next article .

What if you want to know what happened , See the next blog .