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, 37 insertions, 47 deletions

diff --git a/src/common/file_utils.c b/src/common/file_utils.c
index c25713d0e50..a43c82b4b44 100644
--- a/src/common/file_utils.c
+++ b/src/common/file_utils.c
@@ -20,6 +20,7 @@
 #include <unistd.h>
 
 #include "common/file_utils.h"
+#include "fe_utils/logging.h"
 
 
 /* Define PG_FLUSH_DATA_WORKS if we have an implementation for pg_flush_data */
@@ -35,12 +36,11 @@
 #define MINIMUM_VERSION_FOR_PG_WAL	100000
 
 #ifdef PG_FLUSH_DATA_WORKS
-static int pre_sync_fname(const char *fname, bool isdir,
-			   const char *progname);
+static int pre_sync_fname(const char *fname, bool isdir);
 #endif
 static void walkdir(const char *path,
-		int (*action) (const char *fname, bool isdir, const char *progname),
-		bool process_symlinks, const char *progname);
+		int (*action) (const char *fname, bool isdir),
+		bool process_symlinks);
 
 /*
  * Issue fsync recursively on PGDATA and all its contents.
@@ -56,7 +56,6 @@ static void walkdir(const char *path,
  */
 void
 fsync_pgdata(const char *pg_data,
-			 const char *progname,
 			 int serverVersion)
 {
 	bool		xlog_is_symlink;
@@ -79,8 +78,7 @@ fsync_pgdata(const char *pg_data,
 		struct stat st;
 
 		if (lstat(pg_wal, &st) < 0)
-			fprintf(stderr, _("%s: could not stat file \"%s\": %s\n"),
-					progname, pg_wal, strerror(errno));
+			pg_log_error("could not stat file \"%s\": %m", pg_wal);
 		else if (S_ISLNK(st.st_mode))
 			xlog_is_symlink = true;
 	}
@@ -94,10 +92,10 @@ fsync_pgdata(const char *pg_data,
 	 * directory and its contents.
 	 */
 #ifdef PG_FLUSH_DATA_WORKS
-	walkdir(pg_data, pre_sync_fname, false, progname);
+	walkdir(pg_data, pre_sync_fname, false);
 	if (xlog_is_symlink)
-		walkdir(pg_wal, pre_sync_fname, false, progname);
-	walkdir(pg_tblspc, pre_sync_fname, true, progname);
+		walkdir(pg_wal, pre_sync_fname, false);
+	walkdir(pg_tblspc, pre_sync_fname, true);
 #endif
 
 	/*
@@ -109,10 +107,10 @@ fsync_pgdata(const char *pg_data,
 	 * in pg_tblspc, they'll get fsync'd twice.  That's not an expected case
 	 * so we don't worry about optimizing it.
 	 */
-	walkdir(pg_data, fsync_fname, false, progname);
+	walkdir(pg_data, fsync_fname, false);
 	if (xlog_is_symlink)
-		walkdir(pg_wal, fsync_fname, false, progname);
-	walkdir(pg_tblspc, fsync_fname, true, progname);
+		walkdir(pg_wal, fsync_fname, false);
+	walkdir(pg_tblspc, fsync_fname, true);
 }
 
 /*
@@ -121,17 +119,17 @@ fsync_pgdata(const char *pg_data,
  * This is a convenient wrapper on top of walkdir().
  */
 void
-fsync_dir_recurse(const char *dir, const char *progname)
+fsync_dir_recurse(const char *dir)
 {
 	/*
 	 * If possible, hint to the kernel that we're soon going to fsync the data
 	 * directory and its contents.
 	 */
 #ifdef PG_FLUSH_DATA_WORKS
-	walkdir(dir, pre_sync_fname, false, progname);
+	walkdir(dir, pre_sync_fname, false);
 #endif
 
-	walkdir(dir, fsync_fname, false, progname);
+	walkdir(dir, fsync_fname, false);
 }
 
 /*
@@ -150,8 +148,8 @@ fsync_dir_recurse(const char *dir, const char *progname)
  */
 static void
 walkdir(const char *path,
-		int (*action) (const char *fname, bool isdir, const char *progname),
-		bool process_symlinks, const char *progname)
+		int (*action) (const char *fname, bool isdir),
+		bool process_symlinks)
 {
 	DIR		   *dir;
 	struct dirent *de;
@@ -159,8 +157,7 @@ walkdir(const char *path,
 	dir = opendir(path);
 	if (dir == NULL)
 	{
-		fprintf(stderr, _("%s: could not open directory \"%s\": %s\n"),
-				progname, path, strerror(errno));
+		pg_log_error("could not open directory \"%s\": %m", path);
 		return;
 	}
 
@@ -183,20 +180,18 @@ walkdir(const char *path,
 
 		if (sret < 0)
 		{
-			fprintf(stderr, _("%s: could not stat file \"%s\": %s\n"),
-					progname, subpath, strerror(errno));
+			pg_log_error("could not stat file \"%s\": %m", subpath);
 			continue;
 		}
 
 		if (S_ISREG(fst.st_mode))
-			(*action) (subpath, false, progname);
+			(*action) (subpath, false);
 		else if (S_ISDIR(fst.st_mode))
-			walkdir(subpath, action, false, progname);
+			walkdir(subpath, action, false);
 	}
 
 	if (errno)
-		fprintf(stderr, _("%s: could not read directory \"%s\": %s\n"),
-				progname, path, strerror(errno));
+		pg_log_error("could not read directory \"%s\": %m", path);
 
 	(void) closedir(dir);
 
@@ -206,7 +201,7 @@ walkdir(const char *path,
 	 * synced.  Recent versions of ext4 have made the window much wider but
 	 * it's been an issue for ext3 and other filesystems in the past.
 	 */
-	(*action) (path, true, progname);
+	(*action) (path, true);
 }
 
 /*
@@ -218,7 +213,7 @@ walkdir(const char *path,
 #ifdef PG_FLUSH_DATA_WORKS
 
 static int
-pre_sync_fname(const char *fname, bool isdir, const char *progname)
+pre_sync_fname(const char *fname, bool isdir)
 {
 	int			fd;
 
@@ -228,8 +223,7 @@ pre_sync_fname(const char *fname, bool isdir, const char *progname)
 	{
 		if (errno == EACCES || (isdir && errno == EISDIR))
 			return 0;
-		fprintf(stderr, _("%s: could not open file \"%s\": %s\n"),
-				progname, fname, strerror(errno));
+		pg_log_error("could not open file \"%s\": %m", fname);
 		return -1;
 	}
 
@@ -260,7 +254,7 @@ pre_sync_fname(const char *fname, bool isdir, const char *progname)
  * other errors non-fatally.
  */
 int
-fsync_fname(const char *fname, bool isdir, const char *progname)
+fsync_fname(const char *fname, bool isdir)
 {
 	int			fd;
 	int			flags;
@@ -288,8 +282,7 @@ fsync_fname(const char *fname, bool isdir, const char *progname)
 	{
 		if (errno == EACCES || (isdir && errno == EISDIR))
 			return 0;
-		fprintf(stderr, _("%s: could not open file \"%s\": %s\n"),
-				progname, fname, strerror(errno));
+		pg_log_error("could not open file \"%s\": %m", fname);
 		return -1;
 	}
 
@@ -301,8 +294,7 @@ fsync_fname(const char *fname, bool isdir, const char *progname)
 	 */
 	if (returncode != 0 && !(isdir && (errno == EBADF || errno == EINVAL)))
 	{
-		fprintf(stderr, _("%s: could not fsync file \"%s\": %s\n"),
-				progname, fname, strerror(errno));
+		pg_log_error("could not fsync file \"%s\": %m", fname);
 		(void) close(fd);
 		return -1;
 	}
@@ -318,7 +310,7 @@ fsync_fname(const char *fname, bool isdir, const char *progname)
  * an OS crash or power failure.
  */
 int
-fsync_parent_path(const char *fname, const char *progname)
+fsync_parent_path(const char *fname)
 {
 	char		parentpath[MAXPGPATH];
 
@@ -333,7 +325,7 @@ fsync_parent_path(const char *fname, const char *progname)
 	if (strlen(parentpath) == 0)
 		strlcpy(parentpath, ".", MAXPGPATH);
 
-	if (fsync_fname(parentpath, true, progname) != 0)
+	if (fsync_fname(parentpath, true) != 0)
 		return -1;
 
 	return 0;
@@ -345,7 +337,7 @@ fsync_parent_path(const char *fname, const char *progname)
  * Wrapper around rename, similar to the backend version.
  */
 int
-durable_rename(const char *oldfile, const char *newfile, const char *progname)
+durable_rename(const char *oldfile, const char *newfile)
 {
 	int			fd;
 
@@ -356,7 +348,7 @@ durable_rename(const char *oldfile, const char *newfile, const char *progname)
 	 * because it's then guaranteed that either source or target file exists
 	 * after a crash.
 	 */
-	if (fsync_fname(oldfile, false, progname) != 0)
+	if (fsync_fname(oldfile, false) != 0)
 		return -1;
 
 	fd = open(newfile, PG_BINARY | O_RDWR, 0);
@@ -364,8 +356,7 @@ durable_rename(const char *oldfile, const char *newfile, const char *progname)
 	{
 		if (errno != ENOENT)
 		{
-			fprintf(stderr, _("%s: could not open file \"%s\": %s\n"),
-					progname, newfile, strerror(errno));
+			pg_log_error("could not open file \"%s\": %m", newfile);
 			return -1;
 		}
 	}
@@ -373,8 +364,7 @@ durable_rename(const char *oldfile, const char *newfile, const char *progname)
 	{
 		if (fsync(fd) != 0)
 		{
-			fprintf(stderr, _("%s: could not fsync file \"%s\": %s\n"),
-					progname, newfile, strerror(errno));
+			pg_log_error("could not fsync file \"%s\": %m", newfile);
 			close(fd);
 			return -1;
 		}
@@ -384,8 +374,8 @@ durable_rename(const char *oldfile, const char *newfile, const char *progname)
 	/* Time to do the real deal... */
 	if (rename(oldfile, newfile) != 0)
 	{
-		fprintf(stderr, _("%s: could not rename file \"%s\" to \"%s\": %s\n"),
-				progname, oldfile, newfile, strerror(errno));
+		pg_log_error("could not rename file \"%s\" to \"%s\": %m",
+					 oldfile, newfile);
 		return -1;
 	}
 
@@ -393,10 +383,10 @@ durable_rename(const char *oldfile, const char *newfile, const char *progname)
 	 * To guarantee renaming the file is persistent, fsync the file with its
 	 * new name, and its containing directory.
 	 */
-	if (fsync_fname(newfile, false, progname) != 0)
+	if (fsync_fname(newfile, false) != 0)
 		return -1;
 
-	if (fsync_parent_path(newfile, progname) != 0)
+	if (fsync_parent_path(newfile) != 0)
 		return -1;
 
 	return 0;