From: Krzysztof Matczak <krzysztofx.matczak@intel.com>
Date: Wed, 29 Mar 2017 09:39:20 +0000 (+0100)
Subject: utils_message_parser: added message buffer shrinkage
X-Git-Tag: collectd-5.11.0~18^2~5
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=2fe84f82c5bcfcf1d2a5cbcdb27a4af5b3ac6875;p=thirdparty%2Fcollectd.git

utils_message_parser: added message buffer shrinkage

Large message buffer memory allocation that was needed
for handling MCE message flood has significant
performance impact on collectd CPU usage.
This fix adds logic for decreasing message buffer size to
default value (64) if there's nothing to parse.

Change-Id: Ibbaef211e1fe24d53663d717a1899ec719017b2b
Signed-off-by: Krzysztof Matczak <krzysztofx.matczak@intel.com>
---

diff --git a/src/utils_message_parser.c b/src/utils_message_parser.c
index cdffae49d..6b3e4ae83 100644
--- a/src/utils_message_parser.c
+++ b/src/utils_message_parser.c
@@ -88,7 +88,8 @@ static int start_message_assembly(parser_job_data *self) {
 
   /* Resize messages buffer if needed */
   if (self->message_idx >= self->messages_max_len) {
-    INFO(UTIL_NAME ": Exceeded message buffer size: %lu", self->messages_max_len);
+    INFO(UTIL_NAME ": Exceeded message buffer size: %lu",
+         self->messages_max_len);
     if (self->resize_message_buffer(self, self->messages_max_len +
                                               MSG_STOR_INC_STEP) != 0) {
       ERROR(UTIL_NAME ": Insufficient message buffer size: %lu. Remaining "
@@ -116,8 +117,9 @@ static int resize_message_buffer(parser_job_data *self, size_t new_size) {
   self->messages_storage = new_storage;
   self->messages_max_len = new_size;
   /* Fill unused memory with 0 */
-  memset(self->messages_storage + self->message_idx, 0,
-         (self->messages_max_len - self->message_idx) *
+  unsigned int unused_idx = self->message_idx < 0 ? 0 : self->message_idx;
+  memset(self->messages_storage + unused_idx, 0,
+         (self->messages_max_len - unused_idx) *
              sizeof(*(self->messages_storage)));
   return 0;
 }
@@ -140,6 +142,7 @@ static void end_message_assembly(parser_job_data *self) {
     }
   }
   self->messages_storage[self->message_idx].completed = 1;
+  ++self->messages_completed;
   self->message_item_idx = 0;
 }
 
@@ -213,6 +216,7 @@ parser_job_data *message_parser_init(const char *filename,
   parser_job->start_idx = start_idx;
   parser_job->stop_idx = stop_idx;
   parser_job->message_idx = -1;
+  parser_job->messages_completed = 0;
   parser_job->message_patterns =
       calloc(message_patterns_len, sizeof(*(parser_job->message_patterns)));
   if (parser_job->message_patterns == NULL) {
@@ -270,12 +274,14 @@ int message_parser_read(parser_job_data *parser_job, message **messages_storage,
     ERROR(UTIL_NAME ": Invalid parser_job pointer");
     return -1;
   }
-
+  parser_job->messages_completed = 0;
+  _Bool incomplete_msg_found = 0;
   /* Finish incomplete message assembly in this read */
   if (parser_job->message_idx >= 0 &&
       parser_job->messages_storage[parser_job->message_idx].started &&
       !(parser_job->messages_storage[parser_job->message_idx].completed)) {
     INFO(UTIL_NAME ": Found incomplete message from previous read.");
+    incomplete_msg_found = 1;
     message tmp_message = parser_job->messages_storage[parser_job->message_idx];
     int tmp_message_item_idx = parser_job->message_item_idx;
     memset(parser_job->messages_storage, 0,
@@ -285,7 +291,9 @@ int message_parser_read(parser_job_data *parser_job, message **messages_storage,
            sizeof(*(parser_job->messages_storage)));
     parser_job->message_item_idx = tmp_message_item_idx;
     parser_job->message_idx = 0;
-  } else {
+  }
+  /* Reset message buffer after non empty read */
+  else if (parser_job->message_idx >= 0) {
     memset(parser_job->messages_storage, 0,
            parser_job->messages_max_len *
                sizeof(*(parser_job->messages_storage)));
@@ -299,14 +307,13 @@ int message_parser_read(parser_job_data *parser_job, message **messages_storage,
     return -1;
   }
 
-  /* Get no of messagess completed in this read */
-  int messages_completed = 0;
-  for (size_t i = 0; i < parser_job->messages_max_len; i++) {
-    if (parser_job->messages_storage[i].completed)
-      ++messages_completed;
-  }
+  /* Restore initial message buffer size if there's nothing to parse */
+  if (parser_job->messages_completed == 0 &&
+      parser_job->messages_max_len > MSG_STOR_INIT_LEN && !incomplete_msg_found)
+    parser_job->resize_message_buffer(parser_job, MSG_STOR_INIT_LEN);
+
   *messages_storage = parser_job->messages_storage;
-  return messages_completed;
+  return parser_job->messages_completed;
 }
 
 void message_parser_cleanup(parser_job_data *parser_job) {