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IPC Diversion Section

Overview

  • It is a general-purpose implementation of Inter-processing communication between the Server and Client (IPC section).
  • It consists mainly of the following:
  • IPC library implementation source: src, include
  • IPC unit test program: ipc_unit_test

Building Method

  • Building by following steps: bash $ mkdir build $ cd build $ cmake .. $ make
  • The above commands can be executed with the following script: bash $ ./buildtest.sh

The installation described next will be installed on the host PC (/usr/local/). To change the installation destination, change the option passed to cmake.

Example 
$ cmake -DCMAKE_INSTALL_PREFIX=./install ..

Installing Method

bash $ cd build $ sudo make install

When succeeded, the following log will be output. 

[100%] Built target ipc
Install the project...
-- Install configuration: ""
-- Installing: /usr/local/lib/pkgconfig/ipc.pc
-- Installing: /usr/local/lib/libipc.so.1.0.0
-- Installing: /usr/local/lib/libipc.so.1
-- Installing: /usr/local/lib/libipc.so
-- Installing: /usr/local/include/ipc.h
-- Installing: /usr/local/include/ipc_protocol.h

Building Product

  • At last, Building will generate the following:
  • \<installdir>/include/ (External Public header files) bash ipc.h ipc_protocol.h
  • \<installdir>/lib/ (Shared library files) bash libipc.so ( Symbolic link ) libipc.so.1 ( Symbolic link ) libipc.so.1.0.0
  • build/ipc_unit_test/ (Test program executable file) bash ipc_unit_test_client ipc_unit_test_server

How to use

  • This library contains functions for Server and Client; Each has different usage.

Common of Server/Client

  • The user needs to link with the following libraries.
  • libipc.so
  • User includes the library as following.

  • include

    • ipc_protocol.h description is not required; it described later within ipc.h (include ).
  • The header files are used as follows.
  • ipc.h
    • Declare a list of available API functions.
  • ipc_protocol.h
    • Define IPC usage types and data structures for each usage.
  • In libraries, Server and Client communicate using Unix Domain Socket.
  • Generate different communication files for each usage type.
  • By default, a communication file is generated in the execution hierarchy of the Server.
  • For changing the location where generating the communication files, set the environment variable "IPC_DOMAIN_PATH" Example) $ export IPC_DOMAIN_PATH="/tmp" →Unix Domain Socket communication files will be generated under /tmp.

For IC-Service

  • Using this library for IC-Service, use the following values and structures (see ipc_protocol.h).
  • UsageType：IPC_USAGE_TYPE_IC_SERVICE
  • Sending data structure：IPC_DATA_IC_SERVICE_S
  • Changing type callback notification (enum)：IPC_KIND_IC_SERVICE_E
  • Unix Domain Socket communication File name：IpcIcService
  • For IC-Service, the Cluster API library (libcluster_api.so) is the IPC Client.
  • The API for Client is called from libcluster_api.so (described later)

Server API

  • Server applied libipc.so can use the following APIs:
  • ipcServerStart(IPC_USAGE_TYPE_E usageType);
    • Starting the IPC Server for the specified usageType.
  • ipcSendMessage(IPC_USAGE_TYPE_E usageType, const void* pData, signed int size);
    • Sending data to the IPC Client for the specified usageType.
    • Specifying address and size of the sending data by pData and size arguments.
    • Sending data is stored in the Data Pool prepared on the IPC Client side.
  • ipcServerStop(IPC_USAGE_TYPE_E usageType);
    • Terminate the IPC Server for the specified usageType.

Client API

  • The Client applied libipc.so can use the following APIs:
  • ipcClientStart(IPC_USAGE_TYPE_E usageType);
    • Starting the IPC Client for the specified usageType.
    • Connecting with IPC Server for the same usageType.
  • ipcReadDataPool(IPC_USAGE_TYPE_E usageType, void pData, signed int pSize);
    • Reading all data in the Data Pool for the specified usageType.
    • The address where storing the read data is specified in pData. Moreover, the size of storing data is specified in pSize.
    • The contents of the Data Pool output to pData, and the actual read size output to pSize.
  • ipcRegisterCallback(IPC_USAGE_TYPE_E usageType, IPC_CHANGE_NOTIFY_CB changeNotifyCb);
    • When receiving data from the IPC Server, register the callback function for the specified usageType, which receiving notification of which data changed to what.
  • ipcClientStop(IPC_USAGE_TYPE_E usageType);
    • Terminate the IPC Client for the specified usageType.

Unit test executing method

  • Limitations
  • Currently 2020/12/25, this test program connects Server and Client for IC-Service.

  • The Unix domain socket communication files are generated under /tmp/ with the file name ipcIcService.

  • Since Inter processing communication takes place between ipc_unit_test_server and ipc_unit_test_client, so start each one in a separate terminal. Testing example as bellow (Manually operated):

  1. Starting Server and then starting Client bash (Terminal 1) $ ./ipc_unit_test_server command (h=help, q=quit): bash (Terminal 2) $ ./ipc_unit_test_client command (h=help, q=quit):
    At this point, the Server and Client connection for IC-Service is completed. (Executing ipcServerStart () and ipcClientStart ())

  2. Editing and Sending Server data bash (Terminal 1) command (h=help, q=quit):w ←★input w write command (h=help q=goto main menu):2 1 ←★input 2 1 write command (h=help q=goto main menu):70 50 ←★input 70 50 write command (h=help q=goto main menu):l ←★input 1 ★Sending data list is displayed, the result of input contents as below. 2: brake(4) = 1 ←★write command 2 1 result 70: oTempUnitVal(4) = 50 ←★write command 70 50 result write command (h=help q=goto main menu):q ←★input q command (h=help, q=quit):s ←★input s (Executing ipcSendMessage()) ipcSendMessage return:0 command (h=help, q=quit): On the Client side, The callback function should be responding. bash (Terminal 2) command (h=help, q=quit):Enter changeNotifyCb ←★callback kind = 2, size = 4, data=1 ←★Notification of brake value changed to 1 Leave changeNotifyCb ★oFor TempUnitVal change as an IC-Service, there is no callback since it is not monitored.

  3. Check Client side receiving.
    bash (Terminal 2) command (h=help, q=quit):r ←★input r ★Sending data list is displayed, Sending data contained as bellow. 2: brake(4) = 1 70: oTempUnitVal(4) = 50

  4. Exit Client then Server. bash (Terminal 2) command (h=help, q=quit):q bye... $ bash (Terminal 1) command (h=help, q=quit):q bye... $

Adding/Changing IPC usage type method

  • First, the implementation only for IC-Service, but configured to add data for other services easily.
  • Information for each usage type is managed in the following files:
  • include/ipc_protocol.h (External Public header)
  • src/ipc_usage_info_table.c (IPC Internal Source)
  • Adding information for new service or changing information for existed service only by two files above.
  • No changes are required other than .c or .h files in ipc.
  • However, Regarding the application and test program used IPC, It is necessary to take measures according to the adding/changing of the ipc_protocol.h definition.
  • Ideally, code can be generated automatically using tools and else. We do not consider that implementation this time.

Sample code for adding/changing the usage type (Sample code difference)

First, the sample code for adding/changing two files as follow.

Example 1: When adding a new usage type

The following example shows differences when adding the temporary usage type NEW_SERVICE. (Parameters influenced when adding new usage type within the IPC)

diff --git a/include/ipc_protocol.h b/include/ipc_protocol.h
index c0ad861..2bc1115 100644
--- a/include/ipc_protocol.h
+++ b/include/ipc_protocol.h
@@ -6,6 +6,7 @@
 typedef enum {
     IPC_USAGE_TYPE_IC_SERVICE = 0,
     IPC_USAGE_TYPE_FOR_TEST,
+    IPC_USAGE_TYPE_NEW_SERVICE, // Adding usage type
     IPC_USAGE_TYPE_MAX
 } IPC_USAGE_TYPE_E;

@@ -145,4 +146,17 @@ typedef struct {
     signed int test;
 } IPC_DATA_FOR_TEST_S;

+// for IPC_USAGE_TYPE_NEW_SERVICE
+typedef enum { // Preparing only the type which we want to monitor/notify data change
+    IPC_KIND_NS_PARAM1 = 0,
+    IPC_KIND_NS_PARAM2
+} IPC_KIND_NEW_SERVICE_E;
+
+typedef struct { // This part for sending and receiving all data 
+    int param1;
+    int param2;
+    int param3;
+    int param4;
+} IPC_DATA_NEW_SERVICE_S;
+
 #endif // IPC_PROTOCOL_H
diff --git a/src/ipc_usage_info_table.c b/src/ipc_usage_info_table.c
index 976cc73..51264c6 100644
--- a/src/ipc_usage_info_table.c
+++ b/src/ipc_usage_info_table.c
@@ -51,16 +51,24 @@ static IPC_CHECK_CHANGE_INFO_S g_ipcCheckChangeForTest[] = {
     DEFINE_OFFSET_SIZE(IPC_DATA_FOR_TEST_S, test, IPC_KIND_TEST_TEST)
 };

+//   for IPC_USAGE_TYPE_FOR_TEST
+static IPC_CHECK_CHANGE_INFO_S g_ipcCheckChangeNewService[] = { // Describing only the type which we want to monitor/notify data change
+    DEFINE_OFFSET_SIZE(IPC_DATA_NEW_SERVICE_S, param1, IPC_KIND_NS_PARAM1),
+    DEFINE_OFFSET_SIZE(IPC_DATA_NEW_SERVICE_S, param2, IPC_KIND_NS_PARAM2)
+}; //This example not monitoring/notifying changes of param3, param4 data
+
 // == usage info table ==
 //   index of [] is IPC_USAGE_TYPE_E
 IPC_DOMAIN_INFO_S g_ipcDomainInfoList[] =
 {
     {sizeof(IPC_DATA_IC_SERVICE_S), "ipcIcService"},
-    {sizeof(IPC_DATA_FOR_TEST_S), "ipcForTest"}
+    {sizeof(IPC_DATA_FOR_TEST_S), "ipcForTest"},
+    {sizeof(IPC_DATA_NEW_SERVICE_S), "ipcNewService"} // add sending/receiving size information for new Service 
 };

 IPC_CHECK_CHANGE_INFO_TABLE_S g_ipcCheckChangeInfoTbl[] = {
     DEFINE_CHANGE_INFO_TABLE(g_ipcCheckChangeIcService),
-    DEFINE_CHANGE_INFO_TABLE(g_ipcCheckChangeForTest)
+    DEFINE_CHANGE_INFO_TABLE(g_ipcCheckChangeForTest),
+    DEFINE_CHANGE_INFO_TABLE(g_ipcCheckChangeNewService) // Registering data change monitoring table for new Service
 };

Example 2: Deleting part of the existing usage type data

The following example shows differences when deleting the member variable brake from usage sending/receiving data of existing IC-Service. (Parameters influenced when a member variable is deleted within the IPC) 

diff --git a/include/ipc_protocol.h b/include/ipc_protocol.h
index c0ad861..7fed8bf 100644
--- a/include/ipc_protocol.h
+++ b/include/ipc_protocol.h
@@ -13,7 +13,6 @@ typedef enum {
 typedef enum {
     IPC_KIND_ICS_TURN_R = 0,
     IPC_KIND_ICS_TURN_L,
-    IPC_KIND_ICS_BRAKE,
     IPC_KIND_ICS_SEATBELT,
     IPC_KIND_ICS_HIGHBEAM,
     IPC_KIND_ICS_DOOR,
@@ -51,7 +50,6 @@ typedef struct {
     // Telltale
     signed int turnR;
     signed int turnL;
-    signed int brake;
     signed int seatbelt;
     signed int frontRightSeatbelt;
     signed int frontCenterSeatbelt;
diff --git a/src/ipc_usage_info_table.c b/src/ipc_usage_info_table.c
index 976cc73..40ac8df 100644
--- a/src/ipc_usage_info_table.c
+++ b/src/ipc_usage_info_table.c
@@ -12,7 +12,6 @@
 static IPC_CHECK_CHANGE_INFO_S g_ipcCheckChangeIcService[] = {
     DEFINE_OFFSET_SIZE(IPC_DATA_IC_SERVICE_S, turnR, IPC_KIND_ICS_TURN_R),
     DEFINE_OFFSET_SIZE(IPC_DATA_IC_SERVICE_S, turnL, IPC_KIND_ICS_TURN_L),
-    DEFINE_OFFSET_SIZE(IPC_DATA_IC_SERVICE_S, brake, IPC_KIND_ICS_BRAKE),
     DEFINE_OFFSET_SIZE(IPC_DATA_IC_SERVICE_S, seatbelt, IPC_KIND_ICS_SEATBELT),
     DEFINE_OFFSET_SIZE(IPC_DATA_IC_SERVICE_S, highbeam, IPC_KIND_ICS_HIGHBEAM),
     DEFINE_OFFSET_SIZE(IPC_DATA_IC_SERVICE_S, door, IPC_KIND_ICS_DOOR),

Common items regarding new addition of usage type

  • Adding some new enumerations/structures, with addition to existing enumeration/structure. There are no restrictions on the names.

Adding Information to include/ipc_protocol.h

  • For one usage type, adding the following three items of information.
  • Add usage type name.
  • For new usage, Define enumeration for the change notification type.
  • For new usage, Define sending/receiving data structure.
  • Adding usage type name
  • Sample code of this part will be as follow: ```patch typedef enum { IPC_USAGE_TYPE_IC_SERVICE = 0, IPC_USAGE_TYPE_FOR_TEST,
    • IPC_USAGE_TYPE_NEW_SERVICE, // Adding usage type IPC_USAGE_TYPE_MAX } IPC_USAGE_TYPE_E; ```
  • Adding a member for the usage type in enum IPC_USAGE_TYPE_E.
  • Make sure to add it just before IPC_USAGE_TYPE_MAX (Avoiding effect on existing definitions)
  • The value defined here is used to specify the argument usageType such as ipcServerStart() defined in ipc.h.
  • For new usage, Define enumeration for the change notification type.
  • Sample code of this part will be as follow: ```patch +typedef enum { // Preparing only the type which we want to monitor data change
    • IPC_KIND_NS_PARAM1 = 0,
    • IPC_KIND_NS_PARAM2 +} IPC_KIND_NEW_SERVICE_E; ```
  • Adding an enumeration for the data change notification type. Related to the sending/receiving data structures will describe next.
  • This value is used to specify the third argument kind of callback function registered by ipcRegisterCallback().
  • There are no restrictions for naming enumeration and member.
  • For new usage, Define sending/receiving data structure.
  • Sample code of this part will be as follow: ```patch +typedef struct { // This part for sending and receiving all data
    • int param1;
    • int param2;
    • int param3;
    • int param4; +} IPC_DATA_NEW_SERVICE_S; ```
  • For new usage, adding send/receive data structures.
  • The IPC Server will send all the data in the defined structure to the IPC Client.

Regarding adding src/ipc_usage_info_table.c

  • For one usage type, adding the following three items of information.
  • Add a type mapping table for data change notification.
  • Add communication domain information (Communication size and file name).
  • Add mapping table for a relationship between usage and change type.
  • Add a type mapping table for data change notification.
  • Sample code of this part will be as follow: ``` +// for IPC_USAGE_TYPE_FOR_TEST +static IPC_CHECK_CHANGE_INFO_S g_ipcCheckChangeNewService[] = { // Preparing only the type which we want to monitor data change
    • DEFINE_OFFSET_SIZE(IPC_DATA_NEW_SERVICE_S, param1, IPC_KIND_NS_PARAM1),
    • DEFINE_OFFSET_SIZE(IPC_DATA_NEW_SERVICE_S, param2, IPC_KIND_NS_PARAM2) +}; // This example not monitoring/notifying changes of param3, param4 data ```
  • For new usage, add a structure array of IPC_CHECK_CHANGE_INFO_S.
  • Describing a table that maps the definition of change notification type enumeration (defined in ipc_protocol.h) with the data structure members.
  • This table is used for Callback notification of the last receiving data type change when the IPC Client received data from the IPC Server.
  • In structure array, describing multiple macros which defining matching as shown below. c DEFINE_OFFSET_SIZE(<Data structure name>, <Structure member name>, Change notification enumeration member name),

  • In the case of the above sample code, g_ipcCheckChangeNewService[] will be as follows.

    • If the value of param1 is different from the value of the previous receiving, the callback change type IPC_KIND_NS_PARAM1 is notified to the IPC Client.
    • If the value of param2 is different from the value of the previous receiving, the callback change type IPC_KIND_NS_PARAM2 is notified to the IPC Client.
    • For param3 and param4 are not described, the callback does not notify even if the value of the previous receiving is different.

  • Add communication domain information (Communication size and file name).

  • Sample code of this part will be as follow: ```patch IPC_DOMAIN_INFO_S g_ipcDomainInfoList[] = { {sizeof(IPC_DATA_IC_SERVICE_S), "ipcIcService"},
    • {sizeof(IPC_DATA_FOR_TEST_S), "ipcForTest"}
    • {sizeof(IPC_DATA_FOR_TEST_S), "ipcForTest"},
    • {sizeof(IPC_DATA_NEW_SERVICE_S), "ipcNewService"} //add sending/receiving size information for new Service }; ```
  • In structure array g_ipcDomainInfoList[], adding the domain information for new usage.
  • This addition determines the sending/receiving data size used for the newly added usage type and Domain file name used for Unix Domain Socket communication.
  • It is necessary to match the definition order of the enum IPC_USAGE_TYPE_E of ipc_protocol.h, so ensure adding it at the end.
  • Add communication data size structure and the domain filename information to the end of g_ipcDomainInfoList[], as follows: c {sizeof(<communication data structure name>), "domain file name"},
  • Add mapping table for a relationship between usage and change type.
  • Sample code of this part will be as follow: ```patch IPC_CHECK_CHANGE_INFO_TABLE_S g_ipcCheckChangeInfoTbl[] = {i DEFINE_CHANGE_INFO_TABLE(g_ipcCheckChangeIcService),
    • DEFINE_CHANGE_INFO_TABLE(g_ipcCheckChangeForTest)
    • DEFINE_CHANGE_INFO_TABLE(g_ipcCheckChangeForTest),
    • DEFINE_CHANGE_INFO_TABLE(g_ipcCheckChangeNewService) // Registering data change monitoring table for new service }; ```
  • In structure array g_ipcCheckChangeInfoTbl[], adding information about the mapping table for a relationship between new usage and change notification type.
  • It is necessary to match the definition order of the enum IPC_USAGE_TYPE_E of ipc_protocol.h, so ensure adding it at the end.
  • Describing the above-mentioned "change notification type mapping table structure" in the following macro, then add it to the end of g_ipcCheckChangeInfoTbl[]. c DEFINE_CHANGE_INFO_TABLE(<change notification type mapping table structure name>),

Changing of sending data for existing usage

  • When deleting or renaming a member variable in an existing sending data structure in ipc_protocol.h

  • Trying to build each ipc part and application that uses ipc for the service, then fix the part that causing the Compile error.

  • When adding a member variable in an existing sending data structure in ipc_protocol.h

  • Refer to Adding/Changing IPC usage type method, add it to include/ipc_protocol.h and src/ipc_usage_info_table.c.

Supplement

  • In src/ipc_usage_info_table.c, the information is described in the DEFINE_OFFSET_SIZE() macro, which using offsetof() and sizeof() to get the offset and size of member variables from the head of the related structure.
  • In order to make it easier to add usage types, the IPC process does not directly specify variable names in data structures.
  • For each usage, by preparing an offset table of the data structure, it becomes possible to know what variables are in which byte of the sending data.
    • This structure makes it possible to check data change without directly specifying the member variable name inside the IPC process.
  • Adding the usage type according to Adding/Changing IPC usage type method, the IPC inter processing can process new usage.