Unified logging system for command-line programs

This unifies the various ad hoc logging (message printing, error
printing) systems used throughout the command-line programs.

Features:

- Program name is automatically prefixed.

- Message string does not end with newline.  This removes a common
  source of inconsistencies and omissions.

- Additionally, a final newline is automatically stripped, simplifying
  use of PQerrorMessage() etc., another common source of mistakes.

- I converted error message strings to use %m where possible.

- As a result of the above several points, more translatable message
  strings can be shared between different components and between
  frontends and backend, without gratuitous punctuation or whitespace
  differences.

- There is support for setting a "log level".  This is not meant to be
  user-facing, but can be used internally to implement debug or
  verbose modes.

- Lazy argument evaluation, so no significant overhead if logging at
  some level is disabled.

- Some color in the messages, similar to gcc and clang.  Set
  PG_COLOR=auto to try it out.  Some colors are predefined, but can be
  customized by setting PG_COLORS.

- Common files (common/, fe_utils/, etc.) can handle logging much more
  simply by just using one API without worrying too much about the
  context of the calling program, requiring callbacks, or having to
  pass "progname" around everywhere.

- Some programs called setvbuf() to make sure that stderr is
  unbuffered, even on Windows.  But not all programs did that.  This
  is now done centrally.

Soft goals:

- Reduces vertical space use and visual complexity of error reporting
  in the source code.

- Encourages more deliberate classification of messages.  For example,
  in some cases it wasn't clear without analyzing the surrounding code
  whether a message was meant as an error or just an info.

- Concepts and terms are vaguely aligned with popular logging
  frameworks such as log4j and Python logging.

This is all just about printing stuff out.  Nothing affects program
flow (e.g., fatal exits).  The uses are just too varied to do that.
Some existing code had wrappers that do some kind of print-and-exit,
and I adapted those.

I tried to keep the output mostly the same, but there is a lot of
historical baggage to unwind and special cases to consider, and I
might not always have succeeded.  One significant change is that
pg_rewind used to write all error messages to stdout.  That is now
changed to stderr.

Reviewed-by: Donald Dong <xdong@csumb.edu>
Reviewed-by: Arthur Zakirov <a.zakirov@postgrespro.ru>
Discussion: https://www.postgresql.org/message-id/flat/6a609b43-4f57-7348-6480-bd022f924310@2ndquadrant.com

1 files changed, 19 insertions, 22 deletions

diff --git a/src/common/controldata_utils.c b/src/common/controldata_utils.c
index 567281349e0..efca14ba544 100644
--- a/src/common/controldata_utils.c
+++ b/src/common/controldata_utils.c
@@ -28,6 +28,9 @@
 #include "catalog/pg_control.h"
 #include "common/controldata_utils.h"
 #include "common/file_perm.h"
+#ifdef FRONTEND
+#include "fe_utils/logging.h"
+#endif
 #include "port/pg_crc32c.h"
 
 #ifndef FRONTEND
@@ -45,7 +48,7 @@
  * file data is correct.
  */
 ControlFileData *
-get_controlfile(const char *DataDir, const char *progname, bool *crc_ok_p)
+get_controlfile(const char *DataDir, bool *crc_ok_p)
 {
 	ControlFileData *ControlFile;
 	int			fd;
@@ -67,8 +70,8 @@ get_controlfile(const char *DataDir, const char *progname, bool *crc_ok_p)
 #else
 	if ((fd = open(ControlFilePath, O_RDONLY | PG_BINARY, 0)) == -1)
 	{
-		fprintf(stderr, _("%s: could not open file \"%s\" for reading: %s\n"),
-				progname, ControlFilePath, strerror(errno));
+		pg_log_fatal("could not open file \"%s\" for reading: %m",
+					 ControlFilePath);
 		exit(EXIT_FAILURE);
 	}
 #endif
@@ -83,8 +86,7 @@ get_controlfile(const char *DataDir, const char *progname, bool *crc_ok_p)
 					 errmsg("could not read file \"%s\": %m", ControlFilePath)));
 #else
 		{
-			fprintf(stderr, _("%s: could not read file \"%s\": %s\n"),
-					progname, ControlFilePath, strerror(errno));
+			pg_log_fatal("could not read file \"%s\": %m", ControlFilePath);
 			exit(EXIT_FAILURE);
 		}
 #endif
@@ -96,8 +98,8 @@ get_controlfile(const char *DataDir, const char *progname, bool *crc_ok_p)
 							ControlFilePath, r, sizeof(ControlFileData))));
 #else
 		{
-			fprintf(stderr, _("%s: could not read file \"%s\": read %d of %zu\n"),
-					progname, ControlFilePath, r, sizeof(ControlFileData));
+			pg_log_fatal("could not read file \"%s\": read %d of %zu",
+						 ControlFilePath, r, sizeof(ControlFileData));
 			exit(EXIT_FAILURE);
 		}
 #endif
@@ -112,8 +114,7 @@ get_controlfile(const char *DataDir, const char *progname, bool *crc_ok_p)
 #else
 	if (close(fd))
 	{
-		fprintf(stderr, _("%s: could not close file \"%s\": %s\n"),
-				progname, ControlFilePath, strerror(errno));
+		pg_log_fatal("could not close file \"%s\": %m", ControlFilePath);
 		exit(EXIT_FAILURE);
 	}
 #endif
@@ -133,10 +134,10 @@ get_controlfile(const char *DataDir, const char *progname, bool *crc_ok_p)
 #ifndef FRONTEND
 		elog(ERROR, _("byte ordering mismatch"));
 #else
-		printf(_("WARNING: possible byte ordering mismatch\n"
-				 "The byte ordering used to store the pg_control file might not match the one\n"
-				 "used by this program.  In that case the results below would be incorrect, and\n"
-				 "the PostgreSQL installation would be incompatible with this data directory.\n"));
+		pg_log_warning("possible byte ordering mismatch\n"
+					   "The byte ordering used to store the pg_control file might not match the one\n"
+					   "used by this program.  In that case the results below would be incorrect, and\n"
+					   "the PostgreSQL installation would be incompatible with this data directory.");
 #endif
 
 	return ControlFile;
@@ -152,7 +153,7 @@ get_controlfile(const char *DataDir, const char *progname, bool *crc_ok_p)
  * routine in the backend.
  */
 void
-update_controlfile(const char *DataDir, const char *progname,
+update_controlfile(const char *DataDir,
 				   ControlFileData *ControlFile, bool do_sync)
 {
 	int			fd;
@@ -199,8 +200,7 @@ update_controlfile(const char *DataDir, const char *progname,
 	if ((fd = open(ControlFilePath, O_WRONLY | PG_BINARY,
 				   pg_file_create_mode)) == -1)
 	{
-		fprintf(stderr, _("%s: could not open file \"%s\": %s\n"),
-				progname, ControlFilePath, strerror(errno));
+		pg_log_fatal("could not open file \"%s\": %m", ControlFilePath);
 		exit(EXIT_FAILURE);
 	}
 #endif
@@ -221,8 +221,7 @@ update_controlfile(const char *DataDir, const char *progname,
 				 errmsg("could not write file \"%s\": %m",
 						ControlFilePath)));
 #else
-		fprintf(stderr, _("%s: could not write \"%s\": %s\n"),
-				progname, ControlFilePath, strerror(errno));
+		pg_log_fatal("could not write file \"%s\": %m", ControlFilePath);
 		exit(EXIT_FAILURE);
 #endif
 	}
@@ -243,8 +242,7 @@ update_controlfile(const char *DataDir, const char *progname,
 #else
 		if (fsync(fd) != 0)
 		{
-			fprintf(stderr, _("%s: could not fsync file \"%s\": %s\n"),
-					progname, ControlFilePath, strerror(errno));
+			pg_log_fatal("could not fsync file \"%s\": %m", ControlFilePath);
 			exit(EXIT_FAILURE);
 		}
 #endif
@@ -258,8 +256,7 @@ update_controlfile(const char *DataDir, const char *progname,
 				 errmsg("could not close file \"%s\": %m",
 						ControlFilePath)));
 #else
-		fprintf(stderr, _("%s: could not close file \"%s\": %s\n"),
-				progname, ControlFilePath, strerror(errno));
+		pg_log_fatal("could not close file \"%s\": %m", ControlFilePath);
 		exit(EXIT_FAILURE);
 #endif
 	}