postgresql源码学习（44）—— PostmasterMain —— 内存初始化与信号处理函数设置

#include "postgres.h"
 
/*
 * Main entry point for postmaster process.
 *
 * argc/argv are the command line arguments, already processed by the
 * shell script that starts the postmaster.
 *
 * You can spin off other threads after this, but the postmaster's main
 * processing happens here.
 */
int
PostmasterMain(int argc, char *argv[])
{
    // ... 省略其他代码 ...
 
    /*
     * Initialize semaphores.
     */
    if (InitializeSemaphores(numSemas, semSizes, semaphoreNames) != STATUS_OK)
        ereport(FATAL,
                (errcode(ERRCODE_INTERNAL_ERROR),
                 errmsg("could not initialize semaphores")));
 
    /*
     * Initialize other subsystems that need to be running before we start
     * accepting connections.
     */
    // ... 省略其他代码 ...
 
    /*
     * Set up signal handlers.
     */
    // ... 省略其他代码 ...
 
    /*
     * If no data directory was specified, we're done. We didn't want to start
     * up, anyway.
     */
    if (!data_directory)
        return 0;
 
    // ... 省略其他代码 ...
 
    /*
     * Main loop:
     */
    for (;;)
    {
        // ... 省略其他代码 ...
    }
 
    /*
     * Shouldn't get here.
     */
    return 0;
}

这个代码实例省略了PostmasterMain函数中的大部分细节，主要展示了信号处理函数的设置和主循环的开始。在实际的PostgreSQL源代码中，会有更多的初始化工作和错误处理。