Re: [PATCHES] serverlog function (log_destination file)

Looks good to me. The only issue I saw was that the default file name
mentioned in postgresql.conf doesn't match the actual default.

Is this ready to be added to the patch queue?

---------------------------------------------------------------------------

Andreas Pflug wrote:
> Magnus Hagander wrote:
>
> >Specifically about the logs, I still think there is a lot of value to
> >being able to read the logs remotely even if you can't restart
> >postmaster.
> >
> Since I believe that retrieving the logs easily without server file
> access is a feature that's welcomed by many users, here's my proposal.
>
> The attached diff will
> - add a guc-variable log_filename
> - extend log_destination to accept the keyword 'file'
> - elog to that file if configured
> - provide two functions pg_logfile_length() and pg_logfile to obtain the
> contents.
>
> int4 pg_logfile_length()
> cstring pg_logfile(int4 size, int4 position)
> size (may be null meaning max) is the chunk size (max: currently 50000)
> position (may be null meaning -size) is the start position; positive
> counting from log file start, negative from end.
>
>
> Regards,
> Andreas
>

> Index: backend/postmaster/postmaster.c
> ===================================================================
> RCS file: /projects/cvsroot/pgsql-server/src/backend/postmaster/postmaster.c,v
> retrieving revision 1.402
> diff -u -r1.402 postmaster.c
> --- backend/postmaster/postmaster.c 3 Jun 2004 02:08:03 -0000 1.402
> +++ backend/postmaster/postmaster.c 8 Jun 2004 18:07:30 -0000
> @@ -532,6 +532,9 @@
> /* If timezone is not set, determine what the OS uses */
> pg_timezone_initialize();
>
> + /* open alternate logfile, if any */
> + LogFileOpen();
> +
> #ifdef EXEC_BACKEND
> write_nondefault_variables(PGC_POSTMASTER);
> #endif
> Index: backend/storage/ipc/ipc.c
> ===================================================================
> RCS file: /projects/cvsroot/pgsql-server/src/backend/storage/ipc/ipc.c,v
> retrieving revision 1.87
> diff -u -r1.87 ipc.c
> --- backend/storage/ipc/ipc.c 12 Dec 2003 18:45:09 -0000 1.87
> +++ backend/storage/ipc/ipc.c 8 Jun 2004 18:07:31 -0000
> @@ -111,6 +111,8 @@
> on_proc_exit_list[on_proc_exit_index].arg);
>
> elog(DEBUG3, "exit(%d)", code);
> +
> + LogFileClose();
> exit(code);
> }
>
> Index: backend/utils/adt/misc.c
> ===================================================================
> RCS file: /projects/cvsroot/pgsql-server/src/backend/utils/adt/misc.c,v
> retrieving revision 1.34
> diff -u -r1.34 misc.c
> --- backend/utils/adt/misc.c 2 Jun 2004 21:29:29 -0000 1.34
> +++ backend/utils/adt/misc.c 8 Jun 2004 18:07:36 -0000
> @@ -103,3 +103,64 @@
> {
> PG_RETURN_INT32(pg_signal_backend(PG_GETARG_INT32(0),SIGINT));
> }
> +
> +Datum pg_logfile_length(PG_FUNCTION_ARGS)
> +{
> + extern FILE *logfile; // in elog.c
> +
> + if (logfile)
> + PG_RETURN_INT32(ftell(logfile));
> + PG_RETURN_INT32(0);
> +}
> +
> +
> +#define MAXLOGFILECHUNK 50000
> +Datum pg_logfile(PG_FUNCTION_ARGS)
> +{
> + size_t size=MAXLOGFILECHUNK;
> + char *buf=0;
> + size_t nbytes;
> +
> + char *filename = LogFileName();
> + if (filename)
> + {
> + if (!PG_ARGISNULL(0))
> + size = PG_GETARG_INT32(0);
> + if (size > MAXLOGFILECHUNK)
> + {
> + size = MAXLOGFILECHUNK;
> + ereport(WARNING,
> + (errcode(ERRCODE_OUT_OF_MEMORY),
> + errmsg("Maximum size is %d.", MAXLOGFILECHUNK)));
> + }
> +
> + FILE *f=fopen(filename, "r");
> + if (f)
> + {
> + if (PG_ARGISNULL(1))
> + fseek(f, -size, SEEK_END);
> + else
> + {
> + long pos = PG_GETARG_INT32(1);
> + if (pos >= 0)
> + fseek(f, pos, SEEK_SET);
> + else
> + fseek(f, pos, SEEK_END);
> + }
> + buf = palloc(size+1);
> + nbytes = fread(buf, 1, size, f);
> + buf[nbytes] = 0;
> +
> + fclose(f);
> + }
> + else
> + {
> + ereport(WARNING,
> + (errcode(ERRCODE_NO_DATA),
> + errmsg("Could not open log file %s.", filename)));
> + }
> + free(filename);
> + }
> +
> + PG_RETURN_CSTRING(buf);
> +}
> Index: backend/utils/error/elog.c
> ===================================================================
> RCS file: /projects/cvsroot/pgsql-server/src/backend/utils/error/elog.c,v
> retrieving revision 1.140
> diff -u -r1.140 elog.c
> --- backend/utils/error/elog.c 3 Jun 2004 02:08:04 -0000 1.140
> +++ backend/utils/error/elog.c 8 Jun 2004 18:07:39 -0000
> @@ -71,8 +71,10 @@
> PGErrorVerbosity Log_error_verbosity = PGERROR_VERBOSE;
> char *Log_line_prefix = NULL; /* format for extra log line info */
> unsigned int Log_destination = LOG_DESTINATION_STDERR;
> +char *Log_filename = NULL;
>
> bool in_fatal_exit = false;
> +FILE *logfile = NULL;
>
> #ifdef HAVE_SYSLOG
> char *Syslog_facility; /* openlog() parameters */
> @@ -936,6 +938,69 @@
>
>
> /*
> + * Name of configured log file, or NULL
> + * must be freed after usage
> + */
> +char*
> +LogFileName(void)
> +{
> + if (Log_filename && (Log_destination & LOG_DESTINATION_FILE))
> + {
> + if (is_absolute_path(Log_filename))
> + return strdup(Log_filename);
> + else
> + {
> + char *buf = malloc(strlen(DataDir) + strlen(Log_filename) +2);
> + if (!buf)
> + ereport(FATAL,
> + (errcode(ERRCODE_OUT_OF_MEMORY),
> + errmsg("out of memory")));
> +
> + sprintf(buf, "%s/%s", DataDir, Log_filename);
> +
> + return buf;
> + }
> + }
> + return NULL;
> +}
> +
> +
> +/*
> + * Open log file, if configured.
> + */
> +void
> +LogFileOpen(void)
> +{
> + char *filename = LogFileName();
> +
> + if (filename)
> + {
> + LogFileClose();
> +
> + logfile = fopen(filename, "at");
> +
> + if (!logfile)
> + ereport(WARNING,
> + (errcode(ERRCODE_CONFIG_FILE_ERROR),
> + errmsg("could not open log file %s", filename)));
> +
> + free(filename);
> + }
> +}
> +
> +
> +/*
> + * Close log file, if open.
> + */
> +void
> +LogFileClose(void)
> +{
> + if (logfile)
> + fclose(logfile);
> + logfile = NULL;
> +}
> +
> +/*
> * Initialization of error output file
> */
> void
> @@ -1445,6 +1510,11 @@
> if ((Log_destination & LOG_DESTINATION_STDERR) || whereToSendOutput == Debug)
> {
> fprintf(stderr, "%s", buf.data);
> + }
> +
> + if (logfile && (Log_destination & LOG_DESTINATION_FILE))
> + {
> + fprintf(logfile, "%s", buf.data);
> }
>
> pfree(buf.data);
> Index: backend/utils/misc/guc.c
> ===================================================================
> RCS file: /projects/cvsroot/pgsql-server/src/backend/utils/misc/guc.c,v
> retrieving revision 1.210
> diff -u -r1.210 guc.c
> --- backend/utils/misc/guc.c 30 May 2004 23:40:38 -0000 1.210
> +++ backend/utils/misc/guc.c 8 Jun 2004 18:07:47 -0000
> @@ -76,6 +76,8 @@
> static const char *assign_log_destination(const char *value,
> bool doit, GucSource source);
>
> +extern char *Log_filename;
> +
> #ifdef HAVE_SYSLOG
> extern char *Syslog_facility;
> extern char *Syslog_ident;
> @@ -1644,13 +1646,23 @@
> {
> {"log_destination", PGC_POSTMASTER, LOGGING_WHERE,
> gettext_noop("Sets the target for log output."),
> - gettext_noop("Valid values are combinations of stderr, syslog "
> + gettext_noop("Valid values are combinations of stderr, file, syslog "
> "and eventlog, depending on platform."),
> GUC_LIST_INPUT | GUC_REPORT
> },
> &log_destination_string,
> "stderr", assign_log_destination, NULL
> },
> + {
> + {"log_filename", PGC_POSTMASTER, LOGGING_WHERE,
> + gettext_noop("Sets the target filename for log output."),
> + gettext_noop("May be specified as relative to the cluster directory "
> + "or as absolute path."),
> + GUC_LIST_INPUT | GUC_REPORT
> + },
> + &Log_filename,
> + "postgresql.log", NULL, NULL
> + },
>
> #ifdef HAVE_SYSLOG
> {
> @@ -4775,6 +4787,8 @@
>
> if (pg_strcasecmp(tok,"stderr") == 0)
> newlogdest |= LOG_DESTINATION_STDERR;
> + else if (pg_strcasecmp(tok,"file") == 0)
> + newlogdest |= LOG_DESTINATION_FILE;
> #ifdef HAVE_SYSLOG
> else if (pg_strcasecmp(tok,"syslog") == 0)
> newlogdest |= LOG_DESTINATION_SYSLOG;
> Index: backend/utils/misc/postgresql.conf.sample
> ===================================================================
> RCS file: /projects/cvsroot/pgsql-server/src/backend/utils/misc/postgresql.conf.sample,v
> retrieving revision 1.113
> diff -u -r1.113 postgresql.conf.sample
> --- backend/utils/misc/postgresql.conf.sample 7 Apr 2004 05:05:50 -0000 1.113
> +++ backend/utils/misc/postgresql.conf.sample 8 Jun 2004 18:07:48 -0000
> @@ -147,9 +147,10 @@
>
> # - Where to Log -
>
> -#log_destination = 'stderr' # Valid values are combinations of stderr,
> +#log_destination = 'stderr' # Valid values are combinations of stderr, file,
> # syslog and eventlog, depending on
> # platform.
> +#log_filename = 'pgsql.log'
> #syslog_facility = 'LOCAL0'
> #syslog_ident = 'postgres'
>
> Index: include/catalog/pg_proc.h
> ===================================================================
> RCS file: /projects/cvsroot/pgsql-server/src/include/catalog/pg_proc.h,v
> retrieving revision 1.334
> diff -u -r1.334 pg_proc.h
> --- include/catalog/pg_proc.h 2 Jun 2004 21:29:29 -0000 1.334
> +++ include/catalog/pg_proc.h 8 Jun 2004 18:08:03 -0000
> @@ -3588,6 +3588,12 @@
> DATA(insert OID = 2243 ( bit_or PGNSP PGUID 12 t f f f i 1 1560 "1560" _null_ aggregate_dummy - _null_));
> DESCR("bitwise-or bit aggregate");
>
> +DATA(insert OID = 2550( pg_logfile_length PGNSP PGUID 12 f f f f v 0 23 "" _null_ pg_logfile_length - _null_ ));
> +DESCR("length of log file");
> +DATA(insert OID = 2551( pg_logfile PGNSP PGUID 12 f f f f v 2 2275 "23 23" _null_ pg_logfile - _null_ ));
> +DESCR("return log file contents");
> +
> +
> /*
> * Symbolic values for provolatile column: these indicate whether the result
> * of a function is dependent *only* on the values of its explicit arguments,
> Index: include/utils/builtins.h
> ===================================================================
> RCS file: /projects/cvsroot/pgsql-server/src/include/utils/builtins.h,v
> retrieving revision 1.241
> diff -u -r1.241 builtins.h
> --- include/utils/builtins.h 2 Jun 2004 21:29:29 -0000 1.241
> +++ include/utils/builtins.h 8 Jun 2004 18:08:05 -0000
> @@ -356,6 +356,8 @@
> extern Datum current_database(PG_FUNCTION_ARGS);
> extern Datum pg_terminate_backend(PG_FUNCTION_ARGS);
> extern Datum pg_cancel_backend(PG_FUNCTION_ARGS);
> +extern Datum pg_logfile_length(PG_FUNCTION_ARGS);
> +extern Datum pg_logfile(PG_FUNCTION_ARGS);
>
> /* not_in.c */
> extern Datum int4notin(PG_FUNCTION_ARGS);
> Index: include/utils/elog.h
> ===================================================================
> RCS file: /projects/cvsroot/pgsql-server/src/include/utils/elog.h,v
> retrieving revision 1.68
> diff -u -r1.68 elog.h
> --- include/utils/elog.h 5 Apr 2004 03:02:10 -0000 1.68
> +++ include/utils/elog.h 8 Jun 2004 18:08:06 -0000
> @@ -182,8 +182,12 @@
> #define LOG_DESTINATION_STDERR 1
> #define LOG_DESTINATION_SYSLOG 2
> #define LOG_DESTINATION_EVENTLOG 4
> +#define LOG_DESTINATION_FILE 8
>
> /* Other exported functions */
> extern void DebugFileOpen(void);
> +extern char *LogFileName(void);
> +extern void LogFileOpen(void);
> +extern void LogFileClose(void);
>
> #endif /* ELOG_H */

>
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> TIP 7: don't forget to increase your free space map settings

--
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