Logfiles are ordered by their id as follows:

LOGFILE_ERROR   = 1
LOGFILE_MESSAGE = 2
LOGFILE_TRACE   = 4

What is written to file n, will be written to all files m, m>n. Applies to user log writes. Some internal messages are such that they apply to one specific file, such as enable/disable notifications.

log_manager/log_manager.cc

@@ -176,6 +176,7 @@ static int  logmanager_write_log(
         logfile_id_t id,
         bool         flush,
         bool         use_valist,
+        bool         spread_down,
         size_t       len,
         char*        str,
         va_list      valist);
@@ -485,6 +486,9 @@ static logfile_t* logmanager_get_logfile(
  * @param use_valist - in, use
  *          does write involve formatting of the string and use of valist argument
  *
+ * @param spread_down - in, use
+ *          if TRUE, log string is spread to all logs having larger id.
+ *
  * @param str_len - in, use
  *          length of formatted string
  *
@@ -504,6 +508,7 @@ static int logmanager_write_log(
         logfile_id_t  id,
         bool          flush,
         bool          use_valist,
+        bool          spread_down,
         size_t        str_len,
         char*         str,
         va_list       valist)
@@ -523,7 +528,8 @@ static int logmanager_write_log(
              */
             err = logmanager_write_log(LOGFILE_ERROR,
                                        TRUE,
-                                       FALSE, 
+                                       FALSE,
+                                       FALSE,
                                        strlen(errstr)+1,
                                        errstr,
                                        valist);
@@ -548,35 +554,62 @@ static int logmanager_write_log(
             ss_dassert(flush);
             logfile_flush(lf); /**< here we wake up file writer */ 
         } else {
+            int i;
+
             timestamp_len = get_timestamp_len();
+
             /**
-             * Seek write position and register to block buffer.
+             * Write to target log. If spread_down == TRUE, then write also
-             * Then print formatted string to write position.
+             * to all logs with greater logfile id.
+             * LOGFILE_ERROR   = 1,
+             * LOGFILE_MESSAGE = 2,
+             * LOGFILE_TRACE   = 4
+             *
+             * So everything written to error log will appear in message and
+             * trace log. Messages will be written in trace log.
              */
-            wp = blockbuf_get_writepos(&bb, id, timestamp_len-1+str_len, flush);
+            for (i=id; i<=LOGFILE_LAST; i<<=1) {
-            /**
+                    /**< Check if particular log is enabled */
-             * Write timestamp with at most <timestamp_len> characters to wp
+                    if (!(lm->lm_enabled_logfiles & i)) {
-             */
+                            continue;
-            timestamp_len = snprint_timestamp(wp, timestamp_len);
+                    }
-            /**
+                    /**
-             * Write next string to overwrite terminating null character of the
+                     * Seek write position and register to block buffer.
-             * timestamp string.
+                     * Then print formatted string to write position.
-             */
+                     */
-            if (use_valist) {
+                    wp = blockbuf_get_writepos(&bb,
-                vsnprintf(wp+timestamp_len-1, str_len, str, valist);
+                                               (logfile_id_t)i,
-            } else {
+                                               timestamp_len-1+str_len,
-                snprintf(wp+timestamp_len-1, str_len, str);
+                                               flush);
+                    /**
+                     * Write timestamp with at most <timestamp_len> characters
+                     * to wp
+                     */
+                    timestamp_len = snprint_timestamp(wp, timestamp_len);
+                    /**
+                     * Write next string to overwrite terminating null character
+                     * of the timestamp string.
+                     */
+                    if (use_valist) {
+                            vsnprintf(wp+timestamp_len-1, str_len, str, valist);
+                    } else {
+                            snprintf(wp+timestamp_len-1, str_len, str);
+                    }
+                    /** remove double line feed */
+                    if (wp[timestamp_len-1+str_len-2] == '\n') {
+                            wp[timestamp_len-1+str_len-2]=' ';
+                    }
+                    wp[timestamp_len-1+str_len-1]='\n';
+                    
+                    /** lock-free unregistration, includes flush if bb_isfull */
+                    blockbuf_unregister(bb);
+
+                    if (!spread_down) {
+                            break;
+                    }
             }
-            /** remove double line feed */
-            if (wp[timestamp_len-1+str_len-2] == '\n') {
-                wp[timestamp_len-1+str_len-2]=' ';
-            }
-            wp[timestamp_len-1+str_len-1]='\n';
-            
-            /** lock-free unregistration, includes flush if bb_isfull */
-            blockbuf_unregister(bb);
         }
-            
+        
 return_err:
         return err;
 }
@@ -905,7 +938,8 @@ static bool log_set_enabled(
              */
             err = logmanager_write_log(LOGFILE_ERROR,
                                        TRUE,
-                                       FALSE, 
+                                       FALSE,
+                                       FALSE,
                                        strlen(errstr)+1,
                                        errstr,
                                        notused);
@@ -930,6 +964,7 @@ static bool log_set_enabled(
         err = logmanager_write_log(id,
                                    TRUE,
                                    FALSE,
+                                   FALSE,
                                    strlen(logstr)+1,
                                    logstr,
                                    notused);
@@ -964,12 +999,7 @@ int skygw_log_write_flush(
             goto return_err;
         }
         CHK_LOGMANAGER(lm);
-#if 0
+
-        ss_dfprintf(stderr,
-                    "skygw_log_write_flush writes to %s :\n\t%s.\n",
-                    STRLOGID(id),
-                    str);
-#endif
         /**
          * If particular log is disabled only unregister and return.
          */
@@ -991,16 +1021,14 @@ int skygw_log_write_flush(
          * Write log string to buffer and add to file write list.
          */
         va_start(valist, str);
-        err = logmanager_write_log(id, TRUE, TRUE, len, str, valist);
+        err = logmanager_write_log(id, TRUE, TRUE, TRUE, len, str, valist);
         va_end(valist);
 
         if (err != 0) {
             fprintf(stderr, "skygw_log_write_flush failed.\n");
             goto return_unregister;
         }
-#if 0
+
-        ss_dfprintf(stderr, "skygw_log_write_flush succeeed.\n");
-#endif
 return_unregister:
         logmanager_unregister();
 return_err:
@@ -1024,12 +1052,7 @@ int skygw_log_write(
             goto return_err;
         }
         CHK_LOGMANAGER(lm);
-#if 0
+
-        ss_dfprintf(stderr,
-                    "skygw_log_write writes to %s :\n\t%s.\n",
-                    STRLOGID(id),
-                    str);
-#endif
         /**
          * If particular log is disabled only unregister and return.
          */
@@ -1051,16 +1074,14 @@ int skygw_log_write(
          * Write log string to buffer and add to file write list.
          */
         va_start(valist, str);
-        err = logmanager_write_log(id, FALSE, TRUE, len, str, valist);
+        err = logmanager_write_log(id, FALSE, TRUE, TRUE, len, str, valist);
         va_end(valist);
 
         if (err != 0) {
             fprintf(stderr, "skygw_log_write failed.\n");
             goto return_unregister;
         }
-#if 0
+
-        ss_dfprintf(stderr, "skygw_log_write succeeed.\n");
-#endif
 return_unregister:
         logmanager_unregister();
 return_err:
@@ -1080,7 +1101,7 @@ int skygw_log_flush(
             goto return_err;
         }
         CHK_LOGMANAGER(lm);
-        err = logmanager_write_log(id, TRUE, FALSE, 0, NULL, valist);
+        err = logmanager_write_log(id, TRUE, FALSE, FALSE, 0, NULL, valist);
 
         if (err != 0) {
             fprintf(stderr, "skygw_log_flush failed.\n");

log_manager/log_manager.h

@@ -23,11 +23,11 @@ typedef struct fnames_conf_st fnames_conf_t;
 typedef struct logmanager_st  logmanager_t;
 
 typedef enum {
-    LOGFILE_TRACE = 1,
+    LOGFILE_ERROR = 1,
-    LOGFILE_FIRST = LOGFILE_TRACE,
+    LOGFILE_FIRST = LOGFILE_ERROR,
     LOGFILE_MESSAGE = 2,
-    LOGFILE_ERROR = 4,
+    LOGFILE_TRACE = 4,
-    LOGFILE_LAST = LOGFILE_ERROR
+    LOGFILE_LAST = LOGFILE_TRACE
 } logfile_id_t;
 
 typedef enum { FILEWRITER_INIT, FILEWRITER_RUN, FILEWRITER_DONE }

log_manager/test/testlog.c

@@ -40,12 +40,14 @@ static void* thr_run_morelog(void* data);
 #define NTHR 256
 #define NITER 100
 
-#if 0
+
 #define TEST1
+#if 0
 #define TEST2
 #endif
 
 #define TEST3
+#define TEST4
 
 int main(int argc, char* argv[])
 {
@@ -299,7 +301,36 @@ int main(int argc, char* argv[])
         skygw_logmanager_done();
         
 #endif /* TEST 3 */
+
+#if defined(TEST4)
+
+        r = skygw_logmanager_init(argc, argv);
+        ss_dassert(r);
         
+        logstr = ("1.\tWrite to ERROR and thus also to MESSAGE and TRACE logs.");
+        err = skygw_log_write(LOGFILE_ERROR, logstr);
+        ss_dassert(err == 0);
+
+        logstr = ("1.\tWrite to MESSAGE and thus to TRACE logs.");
+        err = skygw_log_write(LOGFILE_MESSAGE, logstr);
+        ss_dassert(err == 0);
+
+        logstr = ("1.\tWrite to TRACE log only.");
+        err = skygw_log_write(LOGFILE_TRACE, logstr);
+        ss_dassert(err == 0);
+
+        skygw_log_disable(LOGFILE_MESSAGE);
+
+        logstr = ("1.\tWrite to ERROR and thus also to TRACE log. MESSAGE is disabled");
+        err = skygw_log_write(LOGFILE_ERROR, logstr);
+        ss_dassert(err == 0);
+        
+        logstr = ("1.\tThis should not appear anywhere since MESSAGE is disabled.");
+        err = skygw_log_write(LOGFILE_MESSAGE, logstr);
+        ss_dassert(err != 0);
+        
+        skygw_logmanager_done();
+#endif /* TEST 4 */
         fprintf(stderr, ".. done.\n");
         return err;
 }