trace mysql queries

ext/memprof.c

@@ -1836,6 +1836,7 @@ Init_memprof()
   install_gc_tracer();
   install_objcount_tracer();
   install_fd_tracer();
+  install_mysql_tracer();
 
   gc_hook = Data_Wrap_Struct(rb_cObject, sourcefile_marker, NULL, NULL);
   rb_global_variable(&gc_hook);

ext/tracers/mysql.c

@@ -0,0 +1,76 @@
+#include <assert.h>
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/time.h>
+
+#include "arch.h"
+#include "bin_api.h"
+#include "tracer.h"
+#include "tramp.h"
+#include "util.h"
+
+struct memprof_mysql_stats {
+  size_t query_calls;
+  double query_time;
+};
+
+static struct tracer tracer;
+static struct memprof_mysql_stats memprof_mysql_stats;
+static int (*orig_real_query)(void *mysql, const char *stmt_str, unsigned long length);
+
+static int
+real_query_tramp(void *mysql, const char *stmt_str, unsigned long length) {
+  struct timeval start, end;
+  double secs = 0;
+  int ret;
+
+  gettimeofday (&start, NULL);
+  ret = orig_real_query(mysql, stmt_str, length);
+  gettimeofday (&end, NULL);
+
+  secs += end.tv_sec - start.tv_sec;
+  secs += (end.tv_usec - start.tv_usec) / 1000000.0;
+
+  memprof_mysql_stats.query_time += secs;
+  memprof_mysql_stats.query_calls++;
+
+  return ret;
+}
+
+static void
+mysql_trace_start() {
+  struct tramp_st2_entry tmp;
+  tmp.addr = real_query_tramp;
+  bin_update_image("mysql_real_query", &tmp, (void **)(&orig_real_query));
+}
+
+static void
+mysql_trace_stop() {
+  // TODO: figure out how to undo the tramp
+}
+
+static void
+mysql_trace_reset() {
+  memset(&memprof_mysql_stats, 0, sizeof(memprof_mysql_stats));
+}
+
+static void
+mysql_trace_dump() {
+  fprintf(stderr, "================ Mysql ====================================\n");
+  fprintf(stderr, " # queries: %zd\n", memprof_mysql_stats.query_calls);
+  fprintf(stderr, " time querying: %fs\n", memprof_mysql_stats.query_time);
+  fprintf(stderr, "===========================================================\n\n");
+}
+
+void install_mysql_tracer()
+{
+  tracer.start = mysql_trace_start;
+  tracer.stop = mysql_trace_stop;
+  tracer.reset = mysql_trace_reset;
+  tracer.dump = mysql_trace_dump;
+  tracer.id = strdup("mysql_tracer");
+
+  trace_insert(&tracer);
+}