serverlog rotation/functions

The attached patch includes serverlog rotation with minimal shared
memory usage as discussed and functions to access it.

Regards,
Andreas

Index: doc/src/sgml/func.sgml
===================================================================
RCS file: /projects/cvsroot/pgsql-server/doc/src/sgml/func.sgml,v
retrieving revision 1.211
diff -u -r1.211 func.sgml
--- doc/src/sgml/func.sgml    25 Jun 2004 17:20:21 -0000    1.211
+++ doc/src/sgml/func.sgml    28 Jun 2004 10:35:09 -0000
@@ -7430,6 +7430,80 @@
    </para>

    <indexterm zone="functions-misc">
+   <primary>pg_logfile_get</primary>
+   </indexterm>
+   <indexterm zone="functions-misc">
+   <primary>pg_logfile_length</primary>
+   </indexterm>
+   <indexterm zone="functions-misc">
+   <primary>pg_logfile_name</primary>
+   </indexterm>
+   <indexterm zone="functions-misc">
+   <primary>pg_logfile_rotate</primary>
+   </indexterm>
+   <para>
+    The functions shown in <xref linkend="functions-misc-logfile">
+    deal with the server log file if configured with log_destination
+    <quote>file</quote>.
+   </para>
+
+   <table id="functions-misc-logfile">
+    <title>Server Logfile Functions</title>
+    <tgroup cols="3">
+     <thead>
+      <row><entry>Name</entry> <entry>Return Type</entry> <entry>Description</entry></row>
+     </thead>
+
+     <tbody>
+      <row>
+       <entry><literal><function>pg_logfile_get</function>(<parameter>size_int4</parameter>,
+       <parameter>offset_int4</parameter>,<parameter>filename_text</parameter>)</literal></entry>
+       <entry><type>cstring</type></entry>
+       <entry>get a part of the current server log file</entry>
+      </row>
+      <row>
+       <entry><literal><function>pg_logfile_length</function>(<paramater>filename_text</parameter>)</literal></entry>
+       <entry><type>int4</type></entry>
+       <entry>return the current length of the server log file</entry>
+      </row>
+      <row>
+       <entry><literal><function>pg_logfile_rotate</function>()</literal></entry>
+       <entry><type>cstring</type></entry>
+       <entry>rotates the server log file and returns the new log file
+       name</entry>
+      </row>
+      <row>
+       <entry><literal><function>pg_logfile_name</function>()</literal></entry>
+       <entry><type>cstring</type></entry>
+       <entry>returns the current server log file name</entry>
+      </row>
+      <row>
+       <entry><literal><function>pg_logfile_rotate</function>()</literal></entry>
+       <entry><type>cstring</type></entry>
+       <entry>rotates the server log file and returns the previous log file
+       name</entry>
+      </row>
+      </tbody>
+</tgroup>
+</table>
+<para>
+The <function>pg_logfile_get</function> function will return the
+       contents of the current server log file, limited by the size
+       parameter. If size is NULL, a server internal limit (currently
+       50000) is applied. The position parameter specifies the
+       starting position of the server log chunk to be returned. A
+       positive number or 0 will be counted from the start of the file,
+       a negative number from the end; if NULL, -size is assumed
+       (i.e. the tail of the log file).
+</para>
+<para>
+Both <function>pg_logfile_get</function> and
+       <function>pg_logfile_length</function> have a filename
+       parameter which may specify the logfile to examine or the
+       current logfile if NULL.
+</para>
+
+   <indexterm zone="functions-misc">
     <primary>pg_cancel_backend</primary>
    </indexterm>

Index: doc/src/sgml/runtime.sgml
===================================================================
RCS file: /projects/cvsroot/pgsql-server/doc/src/sgml/runtime.sgml,v
retrieving revision 1.268
diff -u -r1.268 runtime.sgml
--- doc/src/sgml/runtime.sgml    27 Jun 2004 22:58:19 -0000    1.268
+++ doc/src/sgml/runtime.sgml    28 Jun 2004 10:35:19 -0000
@@ -1721,14 +1721,25 @@
       <listitem>
        <para>
     <productname>PostgreSQL</productname> supports several methods
-     for loggning, including <systemitem>stderr</systemitem> and
-     <systemitem>syslog</systemitem>. On Windows,
-     <systemitem>eventlog</systemitem> is also supported. Set this
+     for logging, including <systemitem>stderr</systemitem>,
+     <systemitem>file></systemitem> and <systemitem>syslog</systemitem>.
+      On Windows, <systemitem>eventlog</systemitem> is also supported. Set this
      option to a list of desired log destinations separated by a
      comma. The default is to log to <systemitem>stderr</systemitem>
      only. This option must be set at server start.
        </para>
       </listitem>
+     </varlistentry>
+
+     <varlistentry id="guc-syslog-facility" xreflabel="log_filename">
+      <term><varname>log_filename</varname> (<type>string</type>)</term>
+       <listitem>
+        <para>
+          This option sets the target filename for the log destination
+          <quote>file</quote> option. It may be specified as absolute
+          path or relative to the <application>cluster directory</application>.
+        </para>
+       </listitem>
      </varlistentry>

      <varlistentry id="guc-syslog-facility" xreflabel="syslog_facility">
Index: src/backend/postmaster/postmaster.c
===================================================================
RCS file: /projects/cvsroot/pgsql-server/src/backend/postmaster/postmaster.c,v
retrieving revision 1.405
diff -u -r1.405 postmaster.c
--- src/backend/postmaster/postmaster.c    24 Jun 2004 21:02:55 -0000    1.405
+++ src/backend/postmaster/postmaster.c    28 Jun 2004 10:35:26 -0000
@@ -729,6 +729,11 @@
     reset_shared(PostPortNumber);

     /*
+     * Opens alternate log file
+     */
+    LogFileInit();
+
+    /*
      * Estimate number of openable files.  This must happen after setting
      * up semaphores, because on some platforms semaphores count as open
      * files.
Index: src/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
--- src/backend/utils/adt/misc.c    2 Jun 2004 21:29:29 -0000    1.34
+++ src/backend/utils/adt/misc.c    28 Jun 2004 10:35:33 -0000
@@ -103,3 +103,138 @@
 {
     PG_RETURN_INT32(pg_signal_backend(PG_GETARG_INT32(0),SIGINT));
 }
+
+
+
+
+extern FILE *logfile; // in elog.c
+#define MAXLOGFILECHUNK 50000
+
+static char *absClusterPath(text *arg)
+{
+    char *filename;
+
+    if (is_absolute_path(VARDATA(arg)))
+        filename=VARDATA(arg);
+    else
+    {
+        filename = palloc(strlen(DataDir)+VARSIZE(arg)+2);
+        sprintf(filename, "%s/%s", DataDir, VARDATA(arg));
+    }
+    return filename;
+}
+
+
+Datum pg_logfile_get(PG_FUNCTION_ARGS)
+{
+    size_t size=MAXLOGFILECHUNK;
+    char *buf=0;
+    size_t nbytes;
+    FILE *f;
+
+    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.", size)));
+    }
+
+    if (PG_ARGISNULL(2))
+        f = logfile;
+    else
+    {
+        /* explicitely named logfile */
+        char *filename = absClusterPath(PG_GETARG_TEXT_P(2));
+        f = fopen(filename, "r");
+        if (!f)
+        {
+            ereport(WARNING,
+                    (errcode_for_file_access(),
+                     errmsg("file not found %s", filename)));
+            PG_RETURN_NULL();
+        }
+    }
+
+    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;
+
+        fseek(f, 0, SEEK_END);
+
+        if (!PG_ARGISNULL(2))
+            fclose(f);
+    }
+
+    if (buf)
+        PG_RETURN_CSTRING(buf);
+    else
+        PG_RETURN_NULL();
+}
+
+
+Datum pg_logfile_length(PG_FUNCTION_ARGS)
+{
+    if (PG_ARGISNULL(0))
+    {
+        if (logfile)
+        {
+            fflush(logfile);
+            PG_RETURN_INT32(ftell(logfile));
+        }
+    }
+    else
+    {
+        struct stat fst;
+        fst.st_size=0;
+        stat(absClusterPath(PG_GETARG_TEXT_P(0)), &fst);
+
+        PG_RETURN_INT32(fst.st_size);
+    }
+    PG_RETURN_INT32(0);
+}
+
+
+Datum pg_logfile_name(PG_FUNCTION_ARGS)
+{
+    char *filename=LogFileName();
+    if (filename)
+    {
+        if (strncmp(filename, DataDir, strlen(DataDir)))
+            PG_RETURN_CSTRING(filename);
+        else
+            PG_RETURN_CSTRING(filename+strlen(DataDir)+1);
+    }
+    PG_RETURN_NULL();
+}
+
+
+Datum pg_logfile_rotate(PG_FUNCTION_ARGS)
+{
+    char *renamedFile = LogFileRotate();
+
+    if (renamedFile)
+    {
+        if (strncmp(renamedFile, DataDir, strlen(DataDir)))
+            PG_RETURN_CSTRING(renamedFile);
+        else
+            PG_RETURN_CSTRING(renamedFile+strlen(DataDir)+1);
+    }
+    else
+        PG_RETURN_NULL();
+}
Index: src/backend/utils/error/elog.c
===================================================================
RCS file: /projects/cvsroot/pgsql-server/src/backend/utils/error/elog.c,v
retrieving revision 1.142
diff -u -r1.142 elog.c
--- src/backend/utils/error/elog.c    24 Jun 2004 21:03:13 -0000    1.142
+++ src/backend/utils/error/elog.c    28 Jun 2004 10:35:36 -0000
@@ -63,7 +63,6 @@
 #include "utils/memutils.h"
 #include "utils/guc.h"

-
 /* Global variables */
 ErrorContextCallback *error_context_stack = NULL;

@@ -71,9 +70,18 @@
 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;                     /* the logfile we're writing to */
+static char logfileName[MAXPGPATH];       /* current filename */
+static long logfileVersion=0;             /* logfile version this backend is currently using */
+
+static FILE *globalLogfileNameFH = NULL;  /* this file contains the current logfile name */
+static long *globalLogfileVersion = NULL; /* logfile version the backend should be using (shared mem) */
+
+
 #ifdef HAVE_SYSLOG
 char       *Syslog_facility;    /* openlog() parameters */
 char       *Syslog_ident;
@@ -140,6 +148,11 @@
 static const char *error_severity(int elevel);
 static void append_with_tabs(StringInfo buf, const char *str);

+static char *logfile_newname(void);
+static void logfile_reopen(void);
+static char *logfile_readname(void);
+static bool logfile_writename(char *fn);
+

 /*
  * errstart --- begin an error-reporting cycle
@@ -931,11 +944,216 @@
     /*
      * And let errfinish() finish up.
      */
+
     errfinish(0);
 }


 /*
+ * Initialize shared mem for logfile rotation
+ */
+
+void
+LogFileInit(void)
+{
+    if (!globalLogfileVersion && Log_filename && (Log_destination & LOG_DESTINATION_FILE))
+    {
+        char buffer[MAXPGPATH];
+        char *fn = logfile_newname();
+        if (fn)
+        {
+            /* create file for logfilename distribution and write initial filename */
+            snprintf(buffer, sizeof(buffer), "%s/global/pglogfile.name", DataDir);
+
+            globalLogfileNameFH = fopen(buffer, "w+");
+            if (!globalLogfileNameFH)
+                             ereport(FATAL,
+                        (errcode_for_file_access(),
+                         errmsg("Logfile distribution file %s couldn't be opened.", buffer)));
+
+            if (!logfile_writename(fn))
+                return;
+
+            /* allocate logfile version shared memory segment for rotation signaling */
+            globalLogfileVersion = ShmemAlloc(sizeof(long));
+            if (!globalLogfileVersion)
+            {
+                ereport(FATAL,
+                        (errcode(ERRCODE_OUT_OF_MEMORY),
+                         errmsg("Out of shared memory")));
+                return;
+            }
+
+            *globalLogfileVersion = 0;
+
+
+            /* open logfile after we successfully initialized */
+            logfile_reopen();
+            pfree(fn);
+        }
+    }
+}
+
+
+/*
+ * Rotate log file
+ */
+char *
+LogFileRotate(void)
+{
+    char *filename;
+    char *oldFilename;
+
+    if (!globalLogfileVersion || !logfileName || !(Log_destination & LOG_DESTINATION_FILE))
+        return NULL;
+
+    filename = logfile_newname();
+    if (!filename)
+        return NULL;
+
+    if (!strcmp(filename, logfileName))
+    {
+        ereport(ERROR,
+                (errcode(ERRCODE_CONFIG_FILE_ERROR),
+                 errmsg("Log_filename not suitable for rotation.")));
+        return NULL;
+    }
+
+    oldFilename = pstrdup(logfileName);
+
+    if (logfile_writename(filename))
+    {
+        *globalLogfileVersion++;
+
+        ereport(NOTICE,
+                (errcode(ERRCODE_WARNING),
+                 errmsg("Opened new log file %s; previous logfile %s", filename, oldFilename)));
+
+        return oldFilename;
+    }
+
+    return NULL;
+}
+
+
+/*
+ * return current log file name
+ */
+char*
+LogFileName(void)
+{
+    if (logfileName)
+        return pstrdup(logfileName);
+    return NULL;
+}
+
+
+/*
+ * creates a new logfile name using current timestamp information
+ */
+static char*
+logfile_newname()
+{
+    char *filetemplate;
+    char *filename;
+    pg_time_t now = time(NULL);
+
+    if (is_absolute_path(Log_filename))
+        filetemplate = pstrdup(Log_filename);
+    else
+    {
+        filetemplate = palloc(strlen(DataDir) + strlen(Log_filename) + 2);
+        sprintf(filetemplate, "%s/%s", DataDir, Log_filename);
+    }
+    filename = palloc(MAXPGPATH);
+    pg_strftime(filename, MAXPGPATH, filetemplate, pg_localtime(&now));
+
+    pfree(filetemplate);
+
+    return filename;
+}
+
+
+/*
+ * return current global logfile name
+ */
+static char*
+logfile_readname(void)
+{
+    if (globalLogfileNameFH)
+    {
+        char *fn=palloc(MAXPGPATH);
+
+        fseek(globalLogfileNameFH, 0, SEEK_SET);
+        if (fread(fn, 1, MAXPGPATH, globalLogfileNameFH) != MAXPGPATH)
+            ereport(FATAL,
+                    (errcode_for_file_access(),
+                     errmsg("Logfile distribution file couldn't be read.")));
+
+        fn[MAXPGPATH-1]=0; /* in case file was corrupted, making sure we're not longer than MAXPGPATH */
+
+        return fn;
+    }
+    return NULL;
+}
+
+
+/*
+ * write global logfile name
+ */
+static bool
+logfile_writename(char *fn)
+{
+    char buffer[MAXPGPATH];
+    memset(buffer, 0, sizeof(buffer));
+    strcpy(buffer, fn);
+
+    fseek(globalLogfileNameFH, 0, SEEK_SET);
+    if (fwrite(buffer, 1, sizeof(buffer), globalLogfileNameFH) != MAXPGPATH)
+    {
+        ereport(FATAL,
+                (errcode_for_file_access(),
+                 errmsg("Logfile distribution file couldn't be written.")));
+        return false;
+    }
+
+    return true;
+}
+
+
+/*
+ * reopen log file.
+ */
+static void
+logfile_reopen(void)
+{
+    if (logfile)
+    {
+        fclose(logfile);
+        logfile = NULL;
+    }
+
+    if ((Log_destination & LOG_DESTINATION_FILE) && globalLogfileVersion && globalLogfileNameFH)
+    {
+        char *fn=logfile_readname();
+        logfileVersion = *globalLogfileVersion;
+        if (fn)
+        {
+            logfile = fopen(fn, "a+");
+
+            if (!logfile)
+                ereport(ERROR,
+                        (errcode_for_file_access(),
+                         errmsg("failed to open log file %s", fn)));
+
+            strcpy(logfileName, fn);
+            pfree(fn);
+        }
+    }
+}
+
+
+/*
  * Initialization of error output file
  */
 void
@@ -1455,6 +1673,24 @@
     if ((Log_destination & LOG_DESTINATION_STDERR) || whereToSendOutput == Debug)
     {
         fprintf(stderr, "%s", buf.data);
+    }
+
+    /* Write to file, if enabled */
+    if (logfile && (Log_destination & LOG_DESTINATION_FILE))
+    {
+        /* check if logfile changed */
+        if (globalLogfileVersion && *globalLogfileVersion != logfileVersion)
+        {
+            logfileVersion = *globalLogfileVersion;
+            logfile_reopen();
+        }
+
+        if (logfile)
+        {
+            fseek(logfile, 0, SEEK_END);
+            fprintf(logfile, "%s", buf.data);
+            fflush(logfile);
+        }
     }

     pfree(buf.data);
Index: src/backend/utils/misc/guc.c
===================================================================
RCS file: /projects/cvsroot/pgsql-server/src/backend/utils/misc/guc.c,v
retrieving revision 1.211
diff -u -r1.211 guc.c
--- src/backend/utils/misc/guc.c    11 Jun 2004 03:54:54 -0000    1.211
+++ src/backend/utils/misc/guc.c    28 Jun 2004 10:35:45 -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.%Y-%m-%d_%H%M%S", NULL, NULL
+    },

 #ifdef HAVE_SYSLOG
     {
@@ -4779,6 +4791,8 @@

         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: src/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
--- src/backend/utils/misc/postgresql.conf.sample    7 Apr 2004 05:05:50 -0000    1.113
+++ src/backend/utils/misc/postgresql.conf.sample    28 Jun 2004 10:35:45 -0000
@@ -147,9 +147,12 @@

 # - 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 = 'postgresql.log.%Y-%m-%d_%H%M%S' # filename if
+                                # 'file' log_destination is used.
+
 #syslog_facility = 'LOCAL0'
 #syslog_ident = 'postgres'

Index: src/include/catalog/pg_proc.h
===================================================================
RCS file: /projects/cvsroot/pgsql-server/src/include/catalog/pg_proc.h,v
retrieving revision 1.339
diff -u -r1.339 pg_proc.h
--- src/include/catalog/pg_proc.h    25 Jun 2004 17:20:28 -0000    1.339
+++ src/include/catalog/pg_proc.h    28 Jun 2004 10:36:00 -0000
@@ -3595,6 +3595,18 @@
 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 = 2546(  int2array_int2vector_eq       PGNSP PGUID 12 f f t f i 2 16 "1005 22" _null_
int2array_int2vector_eq- _null_ )); 
+DESCR("int2array int2vector equal");
+
+DATA(insert OID = 2550(  pg_logfile_get                PGNSP PGUID 12 f f f f v 3 2275 "23 23 25" _null_
pg_logfile_get- _null_ )); 
+DESCR("return log file contents");
+DATA(insert OID = 2551(  pg_logfile_length               PGNSP PGUID 12 f f f f v 1 23 "25" _null_ pg_logfile_length -
_null_)); 
+DESCR("name of log file");
+DATA(insert OID = 2552(  pg_logfile_name               PGNSP PGUID 12 f f f f v 0 2275 "" _null_ pg_logfile_name -
_null_)); 
+DESCR("length of log file");
+DATA(insert OID = 2553(  pg_logfile_rotate               PGNSP PGUID 12 f f f f v 0 2275 "" _null_ pg_logfile_rotate -
_null_)); 
+DESCR("rotate log file");
+
 /*
  * Symbolic values for provolatile column: these indicate whether the result
  * of a function is dependent *only* on the values of its explicit arguments,
Index: src/include/utils/builtins.h
===================================================================
RCS file: /projects/cvsroot/pgsql-server/src/include/utils/builtins.h,v
retrieving revision 1.244
diff -u -r1.244 builtins.h
--- src/include/utils/builtins.h    25 Jun 2004 17:20:29 -0000    1.244
+++ src/include/utils/builtins.h    28 Jun 2004 10:36:03 -0000
@@ -356,6 +356,10 @@
 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_get(PG_FUNCTION_ARGS);
+extern Datum pg_logfile_length(PG_FUNCTION_ARGS);
+extern Datum pg_logfile_name(PG_FUNCTION_ARGS);
+extern Datum pg_logfile_rotate(PG_FUNCTION_ARGS);

 /* not_in.c */
 extern Datum int4notin(PG_FUNCTION_ARGS);
Index: src/include/utils/elog.h
===================================================================
RCS file: /projects/cvsroot/pgsql-server/src/include/utils/elog.h,v
retrieving revision 1.69
diff -u -r1.69 elog.h
--- src/include/utils/elog.h    24 Jun 2004 21:03:42 -0000    1.69
+++ src/include/utils/elog.h    28 Jun 2004 10:36:04 -0000
@@ -182,9 +182,13 @@
 #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 void LogFileInit(void);
+extern char *LogFileRotate(void);
+extern char *LogFileName(void);

 /*
  * Write errors to stderr (or by equal means when stderr is