kcmcp_supervisor.c File Reference

Background worker that launches and supervises the managed KCMCP knowledge-compiler server (the "managed mode" of the KCMCP client). More...

#include "postgres.h"
#include "miscadmin.h"
#include "pgstat.h"
#include "lib/stringinfo.h"
#include "postmaster/bgworker.h"
#include "postmaster/postmaster.h"
#include "storage/latch.h"
#include "storage/ipc.h"
#include "utils/guc.h"
#include <string.h>
#include <signal.h>
#include <unistd.h>
#include <sys/wait.h>
#include <errno.h>
#include "provsql_utils.h"
#include "provsql_shmem.h"
#include "provsql_error.h"

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Macros
#define	WL_EXIT_ON_PM_DEATH   WL_POSTMASTER_DEATH

Functions
static void	kcmcp_sigterm (SIGNAL_ARGS)
static void	kcmcp_sighup (SIGNAL_ARGS)
const char *	provsql_kcmcp_managed_endpoint (void)
	Read the live endpoint of the managed KCMCP server from shared memory (e.g.
static void	publish_endpoint (const char *endpoint)
static char *	build_server_command (const char *tmpl, const char *endpoint)
static pid_t	launch_server (const char *cmd)
static void	kill_server (pid_t child)
static bool	kcmcp_wait (long timeout_ms)
void	provsql_kcmcp_worker (Datum ignored)
void	RegisterProvSQLKCMCPWorker (void)
	Register the supervisor background worker that launches and supervises the managed KCMCP server; called from _PG_init alongside the mmap worker.

Variables
static volatile sig_atomic_t	got_sigterm = false
static volatile sig_atomic_t	got_sighup = false

Detailed Description

Background worker that launches and supervises the managed KCMCP knowledge-compiler server (the "managed mode" of the KCMCP client).

When the provsql.kcmcp_server GUC is non-empty it is a shell command to start a KCMCP server (see doc/source/dev/kc-server-protocol.rst), with the literal {endpoint} replaced by a Unix-socket path this worker picks. The worker forks/execs that command in its own process group, publishes the endpoint in shared memory (read by the in-extension client, kcmcp_client.cpp, for a registry record whose endpoint is 'managed'), and supervises it: on the server's exit it relaunches, on a config reload it restarts a changed command, and on shutdown it kills the whole group. When the GUC is empty the worker simply idles on its latch.

Modeled on RegisterProvSQLMMapWorker (src/provsql_mmap.c); like it, the worker needs only BGWORKER_SHMEM_ACCESS (no database connection): the GUC is a process-global and the endpoint lives in the shared segment.

Definition in file kcmcp_supervisor.c.

Macro Definition Documentation

WL_EXIT_ON_PM_DEATH

#define WL_EXIT_ON_PM_DEATH   WL_POSTMASTER_DEATH

Definition at line 44 of file kcmcp_supervisor.c.

Function Documentation

build_server_command()

char * build_server_command ( const char * tmpl, const char * endpoint )

static

Definition at line 91 of file kcmcp_supervisor.c.

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kcmcp_sighup()

void kcmcp_sighup ( SIGNAL_ARGS )

static

Definition at line 58 of file kcmcp_supervisor.c.

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kcmcp_sigterm()

void kcmcp_sigterm ( SIGNAL_ARGS )

static

Definition at line 50 of file kcmcp_supervisor.c.

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kcmcp_wait()

bool kcmcp_wait ( long timeout_ms )

static

Definition at line 137 of file kcmcp_supervisor.c.

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kill_server()

void kill_server ( pid_t child )

static

Definition at line 122 of file kcmcp_supervisor.c.

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launch_server()

pid_t launch_server ( const char * cmd )

static

Definition at line 106 of file kcmcp_supervisor.c.

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provsql_kcmcp_managed_endpoint()

const char * provsql_kcmcp_managed_endpoint

(

void

)

Read the live endpoint of the managed KCMCP server from shared memory (e.g.

"unix:/tmp/..."), or an empty string when none is running.

Definition at line 66 of file kcmcp_supervisor.c.

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provsql_kcmcp_worker()

void provsql_kcmcp_worker

(

Datum

ignored

)

Definition at line 150 of file kcmcp_supervisor.c.

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publish_endpoint()

void publish_endpoint ( const char * endpoint )

static

Definition at line 78 of file kcmcp_supervisor.c.

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RegisterProvSQLKCMCPWorker()

void RegisterProvSQLKCMCPWorker

(

void

)

Register the supervisor background worker that launches and supervises the managed KCMCP server; called from _PG_init alongside the mmap worker.

Definition at line 236 of file kcmcp_supervisor.c.

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Variable Documentation

got_sighup

volatile sig_atomic_t got_sighup = false

static

Definition at line 48 of file kcmcp_supervisor.c.

got_sigterm

volatile sig_atomic_t got_sigterm = false

static

Definition at line 47 of file kcmcp_supervisor.c.