log: error code generation support

error code and message are generated at compile time by reading a json
file which contains information of elements for each error code.  This
framework provides error handling and ability to do more cleaner log
messages to users.

error-codes.json file contains error description is below format

{
    "ERR_NAME": {"code": ERR_NUM,
                 "message": {"LOCALE": "ERR_MESSAGE"}}
}

At compile time autogen.sh calls gen-headers.py which produces C
header file libglusterfs/src/gf-error-codes.h.  This header has a
function

const char *_gf_get_message (int code);

which returns respective ERR_MESSAGE for given ERR_NUM.

Change-Id: Ieefbf4c470e19a0175c28942e56cec98a3c94ff0
BUG: 928648
Signed-off-by: Bala.FA <barumuga@redhat.com>
Reviewed-on: http://review.gluster.org/4977
Reviewed-by: Niels de Vos <ndevos@redhat.com>
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Vijay Bellur <vbellur@redhat.com>

Makefile.am

@@ -1,7 +1,9 @@
 EXTRA_DIST = autogen.sh \
 	COPYING-GPLV2 COPYING-LGPLV3 \
 	INSTALL README AUTHORS THANKS NEWS \
-	glusterfs.spec glusterfs-api.pc.in
+	glusterfs.spec glusterfs-api.pc.in \
+	error-codes.json gf-error-codes.h.template \
+	gen-headers.py
 
 SUBDIRS = argp-standalone libglusterfs rpc api xlators glusterfsd \
 	$(FUSERMOUNT_SUBDIR) doc extras cli

autogen.sh

@@ -75,6 +75,16 @@ if [ "x$MISSING" != "x" ]; then
   exit 1
 fi
 
+## generate gf-error-codes.h from error-codes.json
+echo "Generate gf-error-codes.h ..."
+if ./gen-headers.py; then
+    if ! mv -fv gf-error-codes.h libglusterfs/src/gf-error-codes.h; then
+	exit 1
+    fi
+else
+    exit 1
+fi
+
 ## Do the autogeneration
 echo Running ${ACLOCAL}...
 $ACLOCAL -I ./contrib/aclocal

error-codes.json

@@ -0,0 +1,4 @@
+{
+    "ERR_DEV": {"code": 9999,
+		"message": {"en": "devel error"}}
+}

gen-headers.py

@@ -0,0 +1,54 @@
+#!/usr/bin/python
+
+import sys
+try:
+    import json
+except ImportError:
+    import simplejson as json
+from string import Template
+
+
+def getLogBook(logFile='error-codes.json'):
+    fp = open(logFile)
+    return json.load(fp)
+
+
+def genCHeader(logBook,
+               infile='gf-error-codes.h.template',
+               outfile='gf-error-codes.h'):
+    fp = open('gf-error-codes.h.template')
+    s = fp.read()
+    fp.close()
+    template = Template(s)
+
+    defineLines = []
+    caseLines = []
+    for name, value in logBook.iteritems():
+        nameDef = "GF_%s" % (name.upper(),)
+        code = value['code']
+        msgNameDef = "%s_MSG" % (nameDef,)
+        msg = value['message']['en']
+
+        defineLines.append("#define %-20s %d" % (nameDef, code))
+        defineLines.append("#define %-20s %s" % (msgNameDef,
+                                                 json.dumps(msg)))
+        caseLines.append("        case %s: return _(%s);" % \
+                             (nameDef, msgNameDef))
+
+    d = {'DEFINES': "\n".join(defineLines),
+         'CASES': "\n".join(caseLines)}
+    #print template.substitute(d)
+
+    fp = open(outfile, 'w')
+    fp.write(template.substitute(d))
+    fp.close()
+
+
+if __name__ == "__main__":
+    try:
+        logBook = getLogBook()
+        genCHeader(logBook)
+        sys.exit(0)
+    except IOError, e:
+        print str(e)
+        sys.exit(-1)

gf-error-codes.h.template

@@ -0,0 +1,33 @@
+/***************************************************************/
+/**                                                           **/
+/**                   DO NOT EDIT THIS FILE                   **/
+/**           THIS IS AUTO-GENERATED FROM LOG BOOK            **/
+/**         YOUR CHANGES WILL BE LOST IN NEXT BUILD           **/
+/**                                                           **/
+/***************************************************************/
+
+#ifndef _GF_ERROR_CODES_H
+#define _GF_ERROR_CODES_H
+
+#include <libintl.h>
+
+#define _(STRING)    gettext(STRING)
+
+
+/** START: ERROR CODE DEFINITIONS **/
+$DEFINES
+/** END: ERROR CODE DEFINITIONS **/
+
+
+/** START: FUNCTION RETURNS MESSAGE OF GIVEN ERROR CODE **/
+const char *
+_gf_get_message (int code) {
+        switch (code) {
+$CASES
+        default: return NULL;
+        }
+}
+/** END: FUNCTION RETURNS MESSAGE OF GIVEN ERROR CODE **/
+
+
+#endif

glusterfs.spec.in

@@ -69,6 +69,9 @@ Source0:          @PACKAGE_NAME@-@PACKAGE_VERSION@.tar.gz
 
 BuildRoot:        %(mktemp -ud %{_tmppath}/%{name}-%{version}-%{release}-XXXXXX)
 
+%if ( 0%{?rhel} && 0%{?rhel} <= 5 )
+BuildRequires:    python-simplejson
+%endif
 %if ( 0%{?_with_systemd:1} )
 BuildRequires:    systemd-units
 Requires(post):   systemd-units

libglusterfs/src/Makefile.am

@@ -29,7 +29,7 @@ libglusterfs_la_SOURCES = dict.c xlator.c logging.c \
 	event-poll.c event-epoll.c
 
 
-nodist_libglusterfs_la_SOURCES = y.tab.c graph.lex.c
+nodist_libglusterfs_la_SOURCES = y.tab.c graph.lex.c gf-error-codes.h
 
 BUILT_SOURCES = graph.lex.c