Le 13/01/2017 à 05:26, Michael Paquier a écrit :
> OK. I have been looking at this patch.
>
> git diff --check is very unhappy, particularly because of
> update_metainfo_datafile().
Sorry, fixed.
> + <para>
> + When logs are written to the file-system their paths, names, and
> + types are recorded in
> + the <xref linkend="storage-pgdata-current-logfiles"> file. This provides
> + a convenient way to find and access log content without establishing a
> + database connection.
> + </para>
> File system is used as a name here. In short, "file-system" -> "file
> system". I think that it would be a good idea to show up the output of
> this file. This could be reworded a bit:
> "When logs are written to the file system, the <xref
> linkend="storage-pgdata-current-logfiles"> file includes the location,
> the name and the type of the logs currently in use. This provides a
> convenient way to find the logs currently in used by the instance."
Changes applied. Output example added:
<programlisting>
$ cat $PGDATA/current_logfiles
stderr pg_log/postgresql-2017-01-13_085812.log
</programlisting>
> @@ -15441,6 +15441,19 @@ SELECT * FROM pg_ls_dir('.') WITH ORDINALITY
> AS t(ls,n);
> </row>
>
> <row>
> +
> <entry><literal><function>pg_current_logfile()</function></literal></entry>
> + <entry><type>text</type></entry>
> + <entry>primary log file name in use by the logging collector</entry>
> + </row>
> +
> + <row>
> +
> <entry><literal><function>pg_current_logfile(<type>text</>)</function></literal></entry>
> + <entry><type>text</type></entry>
> + <entry>log file name, of log in the requested format, in use by the
> + logging collector</entry>
> + </row>
> You could just use one line, using squared brackets for the additional
> argument. The description looks imprecise, perhaps something like that
> would be better: "Log file name currently in use by the logging
> collector".
OK, back to a single row entry with optional parameter.
> +/* in backend/utils/adt/misc.c and backend/postmaster/syslogger.c */
> +/*
> + * Name of file holding the paths, names, and types of the files where
> current
> + * log messages are written, when the log collector is enabled. Useful
> + * outside of Postgres when finding the name of the current log file in the
> + * case of time-based log rotation.
> + */
> Not mentioning the file names here would be better. If this spreads in
> the future updates would likely be forgotten. This paragraph could be
> reworked: "configuration file saving meta-data information about the
> log files currently in use by the system logging process".
Removed.
> --- a/src/include/miscadmin.h
> +++ b/src/include/miscadmin.h
> @@ -466,5 +466,4 @@ extern bool has_rolreplication(Oid roleid);
> /* in access/transam/xlog.c */
> extern bool BackupInProgress(void);
> extern void CancelBackup(void);
> -
> #endif /* MISCADMIN_H */
> Unrelated diff.
Removed
> + /*
> + * Force rewriting last log filename when reloading configuration,
> + * even if rotation_requested is false, log_destination may have
> + * been changed and we don't want to wait the next file rotation.
> + */
> + update_metainfo_datafile();
> +
> }
> I know I am famous for being noisy on such things, but please be
> careful with newline use..
That's ok for me, unnecessary newline removed.
> + else
> + {
> + /* Unknown format, no space. Return NULL to caller. */
> + lbuffer[0] = '\0';
> + break;
> + }
> Hm. I would think that an ERROR is more useful to the user here.
The problem addressed here might never happen unless file corruption but
if you know an error code that can be use in this case I will add the
error message. I can not find any error code usable in this case.
> Perhaps pg_current_logfile() should be marked as STRICT?
I don't think so, the log format parameter is optional, and passing NULL
might be like passing no parameter.
> Would it make sense to have the 0-argument version be a SRF returning
> rows of '(log_destination,location)'? We could just live with this
> function I think, and let the caller filter by logging method.
No, this case have already been eliminated during the previous review.
> + is <literal>NULL</literal>. When multiple logfiles exist, each in a
> + different format, <function>pg_current_logfile</function> called
> s/logfiles/log files/.
Applied.
> Surely the temporary file of current_logfiles should not be included
> in base backups (look at basebackup.c). Documentation needs to reflect
> that as well. Also, should we have current_logfiles in a base backup?
> I would think no.
Done but can't find any documentation about the file exclusion, do you
have a pointer?
> pg_current_logfile() can be run by *any* user. We had better revoke
> its access in system_views.sql!
Why? There is no special information returned by this function unless
the path but it can be retrieve using show log_directory.
Attached is patch v20.
--
Gilles Darold
Consultant PostgreSQL
http://dalibo.com - http://dalibo.org
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 30dd54c..393195f 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4211,6 +4211,17 @@ SELECT * FROM parent WHERE key = 2400;
<primary>server log</primary>
</indexterm>
+ <para>
+ When logs are written to the file system, the <xref
+ linkend="storage-pgdata-current-logfiles"> file includes the type,
+ the location and the name of the logs currently in use. This provides a
+ convenient way to find the logs currently in used by the instance.
+<programlisting>
+$ cat $PGDATA/current_logfiles
+stderr pg_log/postgresql-2017-01-13_085812.log
+</programlisting>
+ </para>
+
<sect2 id="runtime-config-logging-where">
<title>Where To Log</title>
diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index 10e3186..693669b 100644
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -15441,6 +15441,13 @@ SELECT * FROM pg_ls_dir('.') WITH ORDINALITY AS t(ls,n);
</row>
<row>
+ <entry><literal><function>pg_current_logfile(<optional><type>text</></optional>)</function></literal></entry>
+ <entry><type>text</type></entry>
+ <entry>Primary log file name, or log in the requested format,
+ currently in use by the logging collector</entry>
+ </row>
+
+ <row>
<entry><literal><function>pg_my_temp_schema()</function></literal></entry>
<entry><type>oid</type></entry>
<entry>OID of session's temporary schema, or 0 if none</entry>
@@ -15658,6 +15665,39 @@ SET search_path TO <replaceable>schema</> <optional>, <replaceable>schema</>, ..
the time when the postmaster process re-read the configuration files.)
</para>
+ <indexterm>
+ <primary>pg_current_logile</primary>
+ </indexterm>
+
+ <indexterm>
+ <primary>Logging</primary>
+ <secondary>pg_current_logfile function</secondary>
+ </indexterm>
+
+ <para>
+ <function>pg_current_logfile</function> returns, as <type>text</type>,
+ the path of either the csv or stderr log file currently in use by the
+ logging collector. This is a path including the
+ <xref linkend="guc-log-directory"> directory and the log file name.
+ Log collection must be active or the return value
+ is <literal>NULL</literal>. When multiple log files exist, each in a
+ different format, <function>pg_current_logfile</function> called
+ without arguments returns the path of the file having the first format
+ found in the ordered
+ list: <systemitem>stderr</>, <systemitem>csvlog</>.
+ <literal>NULL</literal> is returned when no log file has any of these
+ formats. To request a specific file format supply,
+ as <type>text</type>, either <systemitem>csvlog</>
+ or <systemitem>stderr</> as the value of the optional parameter. The
+ return value is <literal>NULL</literal> when the log format requested
+ is not a configured <xref linkend="guc-log-destination">.
+
+ <function>pg_current_logfiles</function> reflects the content of the
+ <xref linkend="storage-pgdata-current-logfiles"> file. All caveats
+ regards <filename>current_logfiles</filename> content are applicable
+ to <function>pg_current_logfiles</function>' return value.
+ </para>
+
<indexterm>
<primary>pg_my_temp_schema</primary>
</indexterm>
diff --git a/doc/src/sgml/storage.sgml b/doc/src/sgml/storage.sgml
index 5c52824..3ce2a7e 100644
--- a/doc/src/sgml/storage.sgml
+++ b/doc/src/sgml/storage.sgml
@@ -60,6 +60,38 @@ Item
<entry>Subdirectory containing per-database subdirectories</entry>
</row>
+<row id="storage-pgdata-current-logfiles" xreflabel="current_logfiles">
+ <entry>
+ <indexterm>
+ <primary><filename>current_logfiles</filename></primary>
+ </indexterm>
+ <indexterm>
+ <primary>Logging</primary>
+ <secondary><filename>current_logfiles</filename> file</secondary>
+ </indexterm>
+ <filename>current_logfiles</>
+ </entry>
+ <entry>
+ <para>
+ A file recording the log file(s) currently written to by the syslogger
+ and the file's log formats, <systemitem>stderr</>
+ or <systemitem>csvlog</>. Each line of the file is a space separated list of
+ two elements: the log format and the full path to the log file including the
+ value of <xref linkend="guc-log-directory">. The log format must be present
+ in <xref linkend="guc-log-destination"> to be listed in
+ <filename>current_logfiles</filename>.
+ </para>
+
+ <para>
+ The <filename>current_logfiles</filename> file
+ is present only when <xref linkend="guc-logging-collector"> is
+ activated and when at least one of <systemitem>stderr</> or
+ <systemitem>csvlog</> value is present in
+ <xref linkend="guc-log-destination">.
+ </para>
+ </entry>
+</row>
+
<row>
<entry><filename>global</></entry>
<entry>Subdirectory containing cluster-wide tables, such as
diff --git a/src/backend/postmaster/syslogger.c b/src/backend/postmaster/syslogger.c
index 13a0301..80f4204 100644
--- a/src/backend/postmaster/syslogger.c
+++ b/src/backend/postmaster/syslogger.c
@@ -146,7 +146,7 @@ static char *logfile_getname(pg_time_t timestamp, const char *suffix);
static void set_next_rotation_time(void);
static void sigHupHandler(SIGNAL_ARGS);
static void sigUsr1Handler(SIGNAL_ARGS);
-
+static void update_metainfo_datafile(void);
/*
* Main entry point for syslogger process
@@ -348,6 +348,12 @@ SysLoggerMain(int argc, char *argv[])
rotation_disabled = false;
rotation_requested = true;
}
+ /*
+ * Force rewriting last log filename when reloading configuration,
+ * even if rotation_requested is false, log_destination may have
+ * been changed and we don't want to wait the next file rotation.
+ */
+ update_metainfo_datafile();
}
if (Log_RotationAge > 0 && !rotation_disabled)
@@ -511,10 +517,15 @@ int
SysLogger_Start(void)
{
pid_t sysloggerPid;
- char *filename;
if (!Logging_collector)
+ {
+ /* Logging collector is not enabled. We don't know where messages are
+ * logged. Remove outdated file holding the current log filenames.
+ */
+ unlink(LOG_METAINFO_DATAFILE);
return 0;
+ }
/*
* If first time through, create the pipe which will receive stderr
@@ -570,11 +581,15 @@ SysLogger_Start(void)
* a time-based rotation.
*/
first_syslogger_file_time = time(NULL);
- filename = logfile_getname(first_syslogger_file_time, NULL);
- syslogFile = logfile_open(filename, "a", false);
+ if (last_file_name != NULL)
+ pfree(last_file_name);
+
+ last_file_name = logfile_getname(first_syslogger_file_time, NULL);
+
+ syslogFile = logfile_open(last_file_name, "a", false);
- pfree(filename);
+ update_metainfo_datafile();
#ifdef EXEC_BACKEND
switch ((sysloggerPid = syslogger_forkexec()))
@@ -1098,6 +1113,8 @@ open_csvlogfile(void)
pfree(last_csv_file_name);
last_csv_file_name = filename;
+
+ update_metainfo_datafile();
}
/*
@@ -1268,6 +1285,8 @@ logfile_rotate(bool time_based_rotation, int size_rotation_for)
if (csvfilename)
pfree(csvfilename);
+ update_metainfo_datafile();
+
set_next_rotation_time();
}
@@ -1365,3 +1384,61 @@ sigUsr1Handler(SIGNAL_ARGS)
errno = save_errno;
}
+
+/*
+ * Store the name of the file(s) where the log collector, when enabled, writes
+ * log messages. Useful for finding the name(s) of the current log file(s)
+ * when there is time-based logfile rotation. Filenames are stored in a
+ * temporary file and renamed into the final destination for atomicity.
+ */
+static void
+update_metainfo_datafile()
+{
+ FILE *fh;
+
+ if (!(Log_destination & LOG_DESTINATION_STDERR)
+ && !(Log_destination & LOG_DESTINATION_CSVLOG))
+ {
+ unlink(LOG_METAINFO_DATAFILE);
+ return;
+ }
+
+ if ((fh = logfile_open(LOG_METAINFO_DATAFILE_TMP, "w", true)) == NULL)
+ return;
+
+ if (last_file_name && (Log_destination & LOG_DESTINATION_STDERR))
+ {
+ if (fprintf(fh, "stderr %s\n", last_file_name) < 0)
+ {
+ ereport(LOG,
+ (errcode_for_file_access(),
+ errmsg("could not write stderr log file path \"%s\": %m",
+ LOG_METAINFO_DATAFILE_TMP)));
+ fclose(fh);
+ return;
+ }
+ }
+
+ if (last_csv_file_name && (Log_destination & LOG_DESTINATION_CSVLOG))
+ {
+ if (fprintf(fh, "csvlog %s\n", last_csv_file_name) < 0)
+ {
+ ereport(LOG,
+ (errcode_for_file_access(),
+ errmsg("could not write csvlog log file path \"%s\": %m",
+ LOG_METAINFO_DATAFILE_TMP)));
+ fclose(fh);
+ return;
+ }
+ }
+ fclose(fh);
+
+ if (rename(LOG_METAINFO_DATAFILE_TMP, LOG_METAINFO_DATAFILE) != 0)
+ {
+ ereport(LOG,
+ (errcode_for_file_access(),
+ errmsg("could not rename file \"%s\": %m",
+ LOG_METAINFO_DATAFILE_TMP)));
+ return;
+ }
+}
diff --git a/src/backend/replication/basebackup.c b/src/backend/replication/basebackup.c
index 09ecc15..4152d30 100644
--- a/src/backend/replication/basebackup.c
+++ b/src/backend/replication/basebackup.c
@@ -37,6 +37,7 @@
#include "utils/elog.h"
#include "utils/ps_status.h"
#include "utils/timestamp.h"
+#include "postmaster/syslogger.h"
typedef struct
@@ -148,6 +149,9 @@ static const char *excludeFiles[] =
/* Skip auto conf temporary file. */
PG_AUTOCONF_FILENAME ".tmp",
+ /* Skip current log file temporary file */
+ LOG_METAINFO_DATAFILE_TMP,
+
/*
* If there's a backup_label or tablespace_map file, it belongs to a
* backup started by the user with pg_start_backup(). It is *not* correct
diff --git a/src/backend/utils/adt/misc.c b/src/backend/utils/adt/misc.c
index 66d09bc..60ab512 100644
--- a/src/backend/utils/adt/misc.c
+++ b/src/backend/utils/adt/misc.c
@@ -892,3 +892,99 @@ parse_ident(PG_FUNCTION_ARGS)
PG_RETURN_DATUM(makeArrayResult(astate, CurrentMemoryContext));
}
+
+/*
+ * Report current log file used by log collector
+ */
+Datum
+pg_current_logfile(PG_FUNCTION_ARGS)
+{
+ FILE *fd;
+ char lbuffer[MAXPGPATH];
+ char *logfmt;
+ char *log_filepath;
+ char *log_format = lbuffer;
+
+ /* The log format parameter is optional */
+ if (PG_NARGS() == 0 || PG_ARGISNULL(0))
+ logfmt = NULL;
+ else
+ {
+ logfmt = text_to_cstring(PG_GETARG_TEXT_PP(0));
+ if (strcmp(logfmt, "stderr") != 0 && strcmp(logfmt, "csvlog") != 0)
+ {
+ ereport(ERROR,
+ (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+ errmsg("log format \"%s\" is not supported", logfmt),
+ errhint("The supported log formats are \"stderr\""
+ " and \"csvlog\".")));
+ PG_RETURN_NULL();
+ }
+ }
+
+ fd = AllocateFile(LOG_METAINFO_DATAFILE, "r");
+ if (fd == NULL)
+ {
+ if (errno != ENOENT)
+ ereport(ERROR,
+ (errcode_for_file_access(),
+ errmsg("could not read file \"%s\": %m",
+ LOG_METAINFO_DATAFILE)));
+ PG_RETURN_NULL();
+ }
+
+ /*
+ * Read the file to gather current log filename(s) registered
+ * by the syslogger.
+ */
+ while (fgets(lbuffer, sizeof(lbuffer), fd) != NULL)
+ {
+ /* Check for a read error. */
+ if (ferror(fd))
+ {
+ ereport(ERROR,
+ (errcode_for_file_access(),
+ errmsg("could not read file \"%s\": %m",
+ LOG_METAINFO_DATAFILE)));
+ }
+
+ /*
+ * extract log format and log file path from the line
+ * lbuffer == log_format, they share storage
+ */
+ if (log_filepath = strchr(lbuffer, ' '))
+ *log_filepath = '\0';
+ else
+ {
+ /* Unknown format, no space. Return NULL to caller. */
+ lbuffer[0] = '\0';
+ break;
+ }
+ log_filepath++;
+ log_filepath[strcspn(log_filepath, "\n")] = '\0';
+
+ if (logfmt == NULL || strcmp(logfmt, log_format) == 0)
+ {
+ FreeFile(fd);
+ PG_RETURN_TEXT_P(cstring_to_text(log_filepath));
+ }
+ }
+
+ /* Close the current log filename file. */
+ FreeFile(fd);
+
+ PG_RETURN_NULL();
+}
+
+/*
+ * Report current log file used by log collector (1 argument version)
+ *
+ * note: this wrapper is necessary to pass the sanity check in opr_sanity,
+ * which checks that all built-in functions that share the implementing C
+ * function take the same number of arguments
+ */
+Datum
+pg_current_logfile_1arg(PG_FUNCTION_ARGS)
+{
+ return pg_current_logfile(fcinfo);
+}
diff --git a/src/include/catalog/pg_proc.h b/src/include/catalog/pg_proc.h
index 37e022d..eb56e8d 100644
--- a/src/include/catalog/pg_proc.h
+++ b/src/include/catalog/pg_proc.h
@@ -3183,6 +3183,10 @@ DATA(insert OID = 2621 ( pg_reload_conf PGNSP PGUID 12 1 0 0 0 f f f f t f v s
DESCR("reload configuration files");
DATA(insert OID = 2622 ( pg_rotate_logfile PGNSP PGUID 12 1 0 0 0 f f f f t f v s 0 0 16 "" _null_ _null_ _null_ _null_ _null_ pg_rotate_logfile _null_ _null_ _null_ ));
DESCR("rotate log file");
+DATA(insert OID = 3800 ( pg_current_logfile PGNSP PGUID 12 1 0 0 0 f f f f f f v s 0 0 25 "" _null_ _null_ _null_ _null_ _null_ pg_current_logfile _null_ _null_ _null_ ));
+DESCR("current logging collector file location");
+DATA(insert OID = 3801 ( pg_current_logfile PGNSP PGUID 12 1 0 0 0 f f f f f f v s 1 0 25 "25" _null_ _null_ _null_ _null_ _null_ pg_current_logfile_1arg _null_ _null_ _null_ ));
+DESCR("current logging collector file location");
DATA(insert OID = 2623 ( pg_stat_file PGNSP PGUID 12 1 0 0 0 f f f f t f v s 1 0 2249 "25" "{25,20,1184,1184,1184,1184,16}" "{i,o,o,o,o,o,o}" "{filename,size,access,modification,change,creation,isdir}" _null_ _null_ pg_stat_file_1arg _null_ _null_ _null_ ));
DESCR("get information about file");
diff --git a/src/include/postmaster/syslogger.h b/src/include/postmaster/syslogger.h
index c187a5f..ebe3247 100644
--- a/src/include/postmaster/syslogger.h
+++ b/src/include/postmaster/syslogger.h
@@ -87,4 +87,11 @@ extern void write_syslogger_file(const char *buffer, int count, int dest);
extern void SysLoggerMain(int argc, char *argv[]) pg_attribute_noreturn();
#endif
+/*
+ * Name of files saving meta-data information about the log
+ * files currently in use by the system logging process
+ */
+#define LOG_METAINFO_DATAFILE "current_logfiles"
+#define LOG_METAINFO_DATAFILE_TMP LOG_METAINFO_DATAFILE ".tmp"
+
#endif /* _SYSLOGGER_H */
diff --git a/src/include/utils/builtins.h b/src/include/utils/builtins.h
index e1bb344..e2532e6 100644
--- a/src/include/utils/builtins.h
+++ b/src/include/utils/builtins.h
@@ -522,6 +522,8 @@ extern Datum pg_collation_for(PG_FUNCTION_ARGS);
extern Datum pg_relation_is_updatable(PG_FUNCTION_ARGS);
extern Datum pg_column_is_updatable(PG_FUNCTION_ARGS);
extern Datum parse_ident(PG_FUNCTION_ARGS);
+extern Datum pg_current_logfile(PG_FUNCTION_ARGS);
+extern Datum pg_current_logfile_1arg(PG_FUNCTION_ARGS);
/* oid.c */
extern Datum oidin(PG_FUNCTION_ARGS);
--
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