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From: bt23nguyent <[email protected]>
To: Nathan Bossart <[email protected]>
Cc: Daniel Gustafsson <[email protected]>
Cc: Alvaro Herrera <[email protected]>
Cc: [email protected]
Subject: Re: Improve the log message output of basic_archive when basic_archive.archive_directory parameter is not set
Date: Tue, 19 Sep 2023 18:21:59 +0900
Message-ID: <[email protected]> (raw)
In-Reply-To: <20230915143827.GA1912920@nathanxps13>
References: <[email protected]>
	<[email protected]>
	<20230915143827.GA1912920@nathanxps13>

On 2023-09-15 23:38, Nathan Bossart wrote:
> On Fri, Sep 15, 2023 at 02:48:55PM +0200, Daniel Gustafsson wrote:
>>> On 15 Sep 2023, at 12:49, Alvaro Herrera <[email protected]> 
>>> wrote:
>>> 
>>> On 2023-Sep-15, Daniel Gustafsson wrote:
>>> 
>>>> -basic_archive_configured(ArchiveModuleState *state)
>>>> +basic_archive_configured(ArchiveModuleState *state, const char 
>>>> **errmsg)
>>>> 
>>>> The variable name errmsg implies that it will contain the errmsg() 
>>>> data when it
>>>> in fact is used for errhint() data, so it should be named 
>>>> accordingly.
> 
> I have no objection to allowing this callback to provide additional
> information, but IMHO this should use errdetail() instead of errhint(). 
>  In
> the provided patch, the new message explains how the module is not
> configured.  It doesn't hint at how to fix it (although presumably one
> could figure that out pretty easily).
> 
>>>> It's probably better to define the interface as 
>>>> ArchiveCheckConfiguredCB
>>>> functions returning an allocated string in the passed pointer which 
>>>> the caller
>>>> is responsible for freeing.
> 
> That does seem more flexible.
> 
>>> Also note that this callback is documented in archive-modules.sgml, 
>>> so
>>> that needs to be updated as well.  This also means you can't 
>>> backpatch
>>> this change, or you risk breaking external software that implements 
>>> this
>>> interface.
>> 
>> Absolutely, this is master only for v17.
> 
> +1

Thank you for all of your comments!

They are all really constructive and I totally agree with the points you 
brought up.
I have updated the patch accordingly.

Please let me know if you have any further suggestions that I can 
improve more.

Best regards,
Tung Nguyen


Attachments:

  [text/x-diff] v2-0001-Improve-log-message-output-of-basic-archive.patch (5.0K, ../[email protected]/2-v2-0001-Improve-log-message-output-of-basic-archive.patch)
  download | inline diff:
diff --git a/contrib/basic_archive/basic_archive.c b/contrib/basic_archive/basic_archive.c
index 4d78c31859..7b8673f338 100644
--- a/contrib/basic_archive/basic_archive.c
+++ b/contrib/basic_archive/basic_archive.c
@@ -48,7 +48,7 @@ typedef struct BasicArchiveData
 static char *archive_directory = NULL;
 
 static void basic_archive_startup(ArchiveModuleState *state);
-static bool basic_archive_configured(ArchiveModuleState *state);
+static bool basic_archive_configured(ArchiveModuleState *state, char **logdetail);
 static bool basic_archive_file(ArchiveModuleState *state, const char *file, const char *path);
 static void basic_archive_file_internal(const char *file, const char *path);
 static bool check_archive_directory(char **newval, void **extra, GucSource source);
@@ -159,9 +159,15 @@ check_archive_directory(char **newval, void **extra, GucSource source)
  * Checks that archive_directory is not blank.
  */
 static bool
-basic_archive_configured(ArchiveModuleState *state)
+basic_archive_configured(ArchiveModuleState *state, char **logdetail)
 {
-	return archive_directory != NULL && archive_directory[0] != '\0';
+	if (archive_directory == NULL || archive_directory[0] == '\0')
+    {
+        *logdetail = pstrdup("WAL archiving failed because basic_archive.archive_directory is not set");
+        return false;
+    }
+    else
+        return true;
 }
 
 /*
diff --git a/doc/src/sgml/archive-modules.sgml b/doc/src/sgml/archive-modules.sgml
index 7064307d9e..f9f6177844 100644
--- a/doc/src/sgml/archive-modules.sgml
+++ b/doc/src/sgml/archive-modules.sgml
@@ -101,7 +101,7 @@ typedef void (*ArchiveStartupCB) (ArchiveModuleState *state);
     assumes the module is configured.
 
 <programlisting>
-typedef bool (*ArchiveCheckConfiguredCB) (ArchiveModuleState *state);
+typedef bool (*ArchiveCheckConfiguredCB) (ArchiveModuleState *state, char **logdetail);
 </programlisting>
 
     If <literal>true</literal> is returned, the server will proceed with
@@ -112,7 +112,9 @@ typedef bool (*ArchiveCheckConfiguredCB) (ArchiveModuleState *state);
 WARNING:  archive_mode enabled, yet archiving is not configured
 </screen>
     In the latter case, the server will periodically call this function, and
-    archiving will proceed only when it returns <literal>true</literal>.
+    archiving will proceed only when it returns <literal>true</literal>. The
+    archiver may also emit the detail explaining how the module is not configured
+    to the sever log if the archive module has any. 
    </para>
   </sect2>
 
diff --git a/src/backend/archive/shell_archive.c b/src/backend/archive/shell_archive.c
index 157ca4c751..c957a18ee7 100644
--- a/src/backend/archive/shell_archive.c
+++ b/src/backend/archive/shell_archive.c
@@ -23,7 +23,7 @@
 #include "common/percentrepl.h"
 #include "pgstat.h"
 
-static bool shell_archive_configured(ArchiveModuleState *state);
+static bool shell_archive_configured(ArchiveModuleState *state, char **logdetail);
 static bool shell_archive_file(ArchiveModuleState *state,
 							   const char *file,
 							   const char *path);
@@ -43,7 +43,7 @@ shell_archive_init(void)
 }
 
 static bool
-shell_archive_configured(ArchiveModuleState *state)
+shell_archive_configured(ArchiveModuleState *state, char **logdetail)
 {
 	return XLogArchiveCommand[0] != '\0';
 }
diff --git a/src/backend/postmaster/pgarch.c b/src/backend/postmaster/pgarch.c
index 46af349564..2fd1d03b09 100644
--- a/src/backend/postmaster/pgarch.c
+++ b/src/backend/postmaster/pgarch.c
@@ -390,7 +390,8 @@ pgarch_ArchiverCopyLoop(void)
 		{
 			struct stat stat_buf;
 			char		pathname[MAXPGPATH];
-
+			char       *logdetail;
+			
 			/*
 			 * Do not initiate any more archive commands after receiving
 			 * SIGTERM, nor after the postmaster has died unexpectedly. The
@@ -410,10 +411,13 @@ pgarch_ArchiverCopyLoop(void)
 
 			/* can't do anything if not configured ... */
 			if (ArchiveCallbacks->check_configured_cb != NULL &&
-				!ArchiveCallbacks->check_configured_cb(archive_module_state))
+				!ArchiveCallbacks->check_configured_cb(archive_module_state, &logdetail))
 			{
 				ereport(WARNING,
-						(errmsg("archive_mode enabled, yet archiving is not configured")));
+						(errmsg("archive_mode enabled, yet archiving is not configured")),
+						(logdetail != NULL) ? errdetail("%s", logdetail) : 0);
+				if (logdetail != NULL)
+					pfree(logdetail);
 				return;
 			}
 
diff --git a/src/include/archive/archive_module.h b/src/include/archive/archive_module.h
index 679ce5a6db..43bd0ff4c2 100644
--- a/src/include/archive/archive_module.h
+++ b/src/include/archive/archive_module.h
@@ -36,7 +36,7 @@ typedef struct ArchiveModuleState
  * archive modules documentation.
  */
 typedef void (*ArchiveStartupCB) (ArchiveModuleState *state);
-typedef bool (*ArchiveCheckConfiguredCB) (ArchiveModuleState *state);
+typedef bool (*ArchiveCheckConfiguredCB) (ArchiveModuleState *state, char **logdetail);
 typedef bool (*ArchiveFileCB) (ArchiveModuleState *state, const char *file, const char *path);
 typedef void (*ArchiveShutdownCB) (ArchiveModuleState *state);

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  Subject: Re: Improve the log message output of basic_archive when basic_archive.archive_directory parameter is not set
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