Make the size of the in memory ringbuffer for keeping the recent log messages

configureable using --log-ringbuf-size=<num-entries>.

Add an entry in the sysconfig file to set this persistently.

(This used to be ctdb commit c79c2da69bc352f509e7fca4b9172a4b7f23c0f8)

ctdb/common/ctdb_logging.c

@@ -24,7 +24,8 @@
 #include "../include/ctdb_private.h"
 #include "../include/ctdb.h"
 
-#define MAX_LOG_ENTRIES 500000
+int log_ringbuf_size;
+
 #define MAX_LOG_SIZE 128
 
 static int first_entry;
@@ -37,7 +38,7 @@ struct ctdb_log_entry {
 };
 
 
-static struct ctdb_log_entry log_entries[MAX_LOG_ENTRIES];
+static struct ctdb_log_entry *log_entries;
 
 /*
  * this function logs all messages for all levels to a ringbuffer
@@ -46,6 +47,14 @@ static void log_ringbuffer_v(const char *format, va_list ap)
 {
 	int ret;
 
+	if (log_entries == NULL && log_ringbuf_size != 0) {
+		/* Hope this works. We cant log anything if it doesnt anyway */
+		log_entries = malloc(sizeof(struct ctdb_log_entry) * log_ringbuf_size);
+	}
+	if (log_entries == NULL) {
+		return;
+	}
+
 	log_entries[last_entry].message[0] = '\0';
 
 	ret = vsnprintf(&log_entries[last_entry].message[0], MAX_LOG_SIZE, format, ap);
@@ -57,13 +66,13 @@ static void log_ringbuffer_v(const char *format, va_list ap)
 	log_entries[last_entry].t = timeval_current();
 
 	last_entry++;
-	if (last_entry >= MAX_LOG_ENTRIES) {
+	if (last_entry >= log_ringbuf_size) {
 		last_entry = 0;
 	}
 	if (first_entry == last_entry) {
 		first_entry++;
 	}
-	if (first_entry >= MAX_LOG_ENTRIES) {
+	if (first_entry >= log_ringbuf_size) {
 		first_entry = 0;
 	}
 }
@@ -100,9 +109,13 @@ static void ctdb_collect_log(struct ctdb_context *ctdb, struct ctdb_get_log_addr
 		struct tm *tm;
 		char tbuf[100];
 
+		if (log_entries == NULL) {
+			break;
+		}
+
 		if (log_entries[tmp_entry].level > log_addr->level) {
 			tmp_entry++;
-			if (tmp_entry >= MAX_LOG_ENTRIES) {
+			if (tmp_entry >= log_ringbuf_size) {
 				tmp_entry = 0;
 			}
 		 	continue;
@@ -116,7 +129,7 @@ static void ctdb_collect_log(struct ctdb_context *ctdb, struct ctdb_get_log_addr
 		}
 
 		tmp_entry++;
-		if (tmp_entry >= MAX_LOG_ENTRIES) {
+		if (tmp_entry >= log_ringbuf_size) {
 			tmp_entry = 0;
 		}
 	}

ctdb/config/ctdb.init

@@ -102,6 +102,7 @@ build_ctdb_options () {
     maybe_set "--no-lmaster"             "$CTDB_CAPABILITY_LMASTER"   "no"
     maybe_set "--lvs --single-public-ip" "$CTDB_LVS_PUBLIC_IP"
     maybe_set "--script-log-level"       "$CTDB_SCRIPT_LOG_LEVEL"
+    maybe_set "--log-ringbuf-size"       "$CTDB_LOG_RINGBUF_SIZE"
     maybe_set "--syslog"                 "$CTDB_SYSLOG"               "yes"
     maybe_set "--max-persistent-check-errors" "$CTDB_MAX_PERSISTENT_CHECK_ERRORS"
 }

ctdb/config/ctdb.sysconfig

@@ -208,6 +208,13 @@ CTDB_DEBUGLEVEL=ERR
 # "-1" means wait forever.
 # CTDB_MAX_PERSISTENT_CHECK_ERRORS=0
 
+# All log entries up to level 9 are also collected into a in-memory ringbuffer
+# in addition to the log that is written to the log file.
+# This parameter controls how many entries we allow for this in memory log
+# CTDB_LOG_RINGBUF_SIZE=500000
+
+# 
+#
 # set any default tuning options for ctdb
 # use CTDB_SET_XXXX=value where XXXX is the name of the tuning
 # variable

ctdb/include/ctdb_private.h

@@ -1538,8 +1538,12 @@ struct ctdb_get_log_addr {
 	int32_t level;
 };
 
+extern int log_ringbuf_size;
+
 int32_t ctdb_control_get_log(struct ctdb_context *ctdb, TDB_DATA addr);
 int32_t ctdb_control_clear_log(struct ctdb_context *ctdb);
+
+
 struct ctdb_log_state *ctdb_fork_with_logging(TALLOC_CTX *mem_ctx,
 					      struct ctdb_context *ctdb,
 					      void (*logfn)(const char *, uint16_t, void *),

ctdb/server/ctdbd.c

@@ -143,6 +143,7 @@ int main(int argc, const char *argv[])
 		{ "max-persistent-check-errors", 0, POPT_ARG_INT,
 		  &options.max_persistent_check_errors, 0,
 		  "max allowed persistent check errors (default 0)", NULL },
+		{ "log-ringbuf-size", 0, POPT_ARG_INT, &log_ringbuf_size, DEBUG_ERR, "Number of log messages we can store in the memory ringbuffer", NULL },
 		POPT_TABLEEND
 	};
 	int opt, ret;