[PATCH 1/3] Initial implementation of low level logging routines.

[david at tethera.net]

From: David Bremner <bremner at unb.ca>

notmuch_log_open: open a log file; just a wrapper around open(2)
notmuch_log_append: atomically append a buffer (character array) to a log file

Based on per-write file locking, performance will have to be tested.
---
 Makefile.local   |    1 +
 notmuch-client.h |   10 +++++
 notmuch-config.c |   15 ++++++++
 notmuch-log.c    |  102 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 128 insertions(+), 0 deletions(-)
 create mode 100644 notmuch-log.c

diff --git a/Makefile.local b/Makefile.local
index ade8412..8dbda15 100644
--- a/Makefile.local
+++ b/Makefile.local
@@ -240,6 +240,7 @@ notmuch_client_srcs =		\
 	notmuch-config.c	\
 	notmuch-count.c		\
 	notmuch-dump.c		\
+	notmuch-log.c		\
 	notmuch-new.c		\
 	notmuch-reply.c		\
 	notmuch-restore.c	\
diff --git a/notmuch-client.h b/notmuch-client.h
index 20be43b..0422b1c 100644
--- a/notmuch-client.h
+++ b/notmuch-client.h
@@ -191,6 +191,16 @@ notmuch_config_set_new_tags (notmuch_config_t *config,
 			     const char *new_tags[],
 			     size_t length);
 
+const char *
+notmuch_config_get_log_path (notmuch_config_t *config,
+			     const char *name);
+
+int
+notmuch_log_open (const char *path);
+
+notmuch_status_t
+notmuch_log_append (int file_desc, const char *buffer, size_t len);
+
 notmuch_bool_t
 debugger_is_active (void);
 
diff --git a/notmuch-config.c b/notmuch-config.c
index cf30603..c01e8f4 100644
--- a/notmuch-config.c
+++ b/notmuch-config.c
@@ -562,3 +562,18 @@ notmuch_config_set_new_tags (notmuch_config_t *config,
     config->new_tags = NULL;
 }
 
+const char *
+notmuch_config_get_log_path (notmuch_config_t *config, const char *name)
+{
+    char *path, *rpath;
+
+    path= g_key_file_get_string (config->key_file,
+				 "log", name, NULL);
+    if (path != NULL) {
+	rpath = talloc_strdup (config, path);
+	free (path);
+	return rpath;
+    } else {
+	return NULL;
+    }
+}
diff --git a/notmuch-log.c b/notmuch-log.c
new file mode 100644
index 0000000..c4ddcd3
--- /dev/null
+++ b/notmuch-log.c
@@ -0,0 +1,102 @@
+
+/* notmuch - Not much of an email program, (just index and search)
+ *
+ * Copyright © 2010 David Bremner
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see http://www.gnu.org/licenses/ .
+ *
+ * Author: David Bremner <david at tethera.net>
+ */
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+
+#include "notmuch-client.h"
+/*
+   Look a key up in the config file; open the corresponding file as a
+   log.
+
+   Return a file descriptor to the open log file, or -1 if an error
+   occurs.
+  */
+
+int
+notmuch_log_open (const char *path)
+{
+    int fd;
+
+    fd = open (path, O_CREAT|O_WRONLY|O_APPEND);
+    if (fd < 0) {
+	fprintf (stderr, "Failed to open %s: %s\n",
+		 path, strerror (errno));
+    }
+
+    return fd;
+}
+
+notmuch_status_t
+notmuch_log_append (int file_desc, const char *buffer, size_t len){
+
+    struct flock lock;
+
+    lock.l_type = F_WRLCK;
+    lock.l_whence = SEEK_SET;
+    lock.l_start = 0;
+    lock.l_len = 0;
+
+    if (fcntl (file_desc, F_SETLKW, &lock) != 0) {
+	fprintf (stderr, "Failed to lock  %s\n",
+		 strerror (errno));
+
+	return NOTMUCH_STATUS_FILE_ERROR;
+    }
+
+    while (len > 0)
+    {
+	int written;
+
+	written = write(file_desc, buffer, len);
+	if (written < 0 || (written == 0 && errno !=0))
+	{
+	    fprintf (stderr, "Failed to write %zd characters: %s\n",
+		     len, strerror (errno));
+
+	    return NOTMUCH_STATUS_FILE_ERROR;
+	}
+
+	len -= written;
+	buffer += written;
+
+    }
+
+    if (fdatasync (file_desc) != 0) {
+	fprintf (stderr, "Failed to sync:  %s\n",
+		 strerror (errno));
+
+	return NOTMUCH_STATUS_FILE_ERROR;
+    }
+
+    lock.l_type=F_UNLCK;
+
+    if (fcntl (file_desc, F_SETLK, &lock) != 0) {
+	fprintf (stderr, "Failed to unlock:  %s\n",
+		 strerror (errno));
+
+	return NOTMUCH_STATUS_FILE_ERROR;
+    }
+
+    return NOTMUCH_STATUS_SUCCESS;
+}
-- 
1.7.1