pg_callgraph.patch

*** a/src/backend/postmaster/pgstat.c
--- b/src/backend/postmaster/pgstat.c
***************
*** 174,179 **** static TabStatusArray *pgStatTabList = NULL;
--- 174,186 ----
  static HTAB *pgStatFunctions = NULL;
  
  /*
+  * Call graph
+  */
+ static List *call_stack       = NIL;
+ static HTAB *call_graph       = NULL;
+ static HTAB *seen_call_graphs = NULL;
+ 
+ /*
   * Indicates if backend has some function stats that it hasn't yet
   * sent to the collector.
   */
***************
*** 286,291 **** static void pgstat_recv_bgwriter(PgStat_MsgBgWriter *msg, int len);
--- 293,299 ----
  static void pgstat_recv_funcstat(PgStat_MsgFuncstat *msg, int len);
  static void pgstat_recv_funcpurge(PgStat_MsgFuncpurge *msg, int len);
  static void pgstat_recv_recoveryconflict(PgStat_MsgRecoveryConflict *msg, int len);
+ static int pgstat_edge_comparator(const void *arg1, const void *arg2);
  
  
  /* ------------------------------------------------------------
***************
*** 1384,1389 **** pgstat_init_function_usage(FunctionCallInfoData *fcinfo,
--- 1392,1398 ----
  						   PgStat_FunctionCallUsage *fcu)
  {
  	PgStat_BackendFunctionEntry *htabent;
+ 	PgStat_CallGraphEdge call_graph_edge;
  	bool		found;
  
  	if (pgstat_track_functions <= fcinfo->flinfo->fn_stats)
***************
*** 1424,1429 **** pgstat_init_function_usage(FunctionCallInfoData *fcinfo,
--- 1433,1469 ----
  
  	/* get clock time as of function start */
  	INSTR_TIME_SET_CURRENT(fcu->f_start);
+ 
+ 	if (!call_graph)
+ 	{
+ 		/* First time through - initialize call graph hash */
+ 		HASHCTL		hash_ctl;
+ 
+ 		memset(&hash_ctl, 0, sizeof(hash_ctl));
+ 		hash_ctl.keysize = sizeof(PgStat_CallGraphEdge);
+ 		hash_ctl.entrysize = sizeof(PgStat_CallGraphEdge);
+ 		hash_ctl.hash = tag_hash;
+ 		call_graph = hash_create("Call graph",
+ 								PGSTAT_FUNCTION_HASH_SIZE,
+ 								&hash_ctl,
+ 								HASH_ELEM | HASH_FUNCTION);
+ 	}
+ 
+ 	if (call_stack != NIL)
+ 	{
+ 		/* Non-empty call stack which means we are in a subroutine called from a parent */
+ 
+ 		/* Set the oid of the caller and called function */
+ 		
+ 		call_graph_edge.caller_oid = lfirst_oid(call_stack->head);
+ 		call_graph_edge.called_oid = fcinfo->flinfo->fn_oid;
+ 
+ 		/* Set the unique combination of caller/called oid, if not already set */
+ 		hash_search(call_graph, &call_graph_edge, HASH_ENTER, NULL);
+ 	}
+ 	/* Add called function oid to the head of the call stack list */
+ 	call_stack = lcons_oid(fcinfo->flinfo->fn_oid, call_stack);
+ 
  }
  
  /*
***************
*** 1494,1499 **** pgstat_end_function_usage(PgStat_FunctionCallUsage *fcu, bool finalize)
--- 1534,1542 ----
  
  	/* indicate that we have something to send */
  	have_function_stats = true;
+ 
+ 	/* Remove this function OID from call stack, if it's non-empty the new head will be the parent OID */
+ 	call_stack = list_delete_first(call_stack);
  }
  
  
***************
*** 1772,1777 **** AtEOXact_PgStat(bool isCommit)
--- 1815,1873 ----
  {
  	PgStat_SubXactStatus *xact_state;
  
+ 	/* Log call graph */
+ 	PgStat_CallGraphEdge	*call_graph_edge;
+ 	HASH_SEQ_STATUS			call_graph_stat;
+ 	int						num_edges = 0;
+ 	bool					found;
+ 	char					call_graph_string[16384];
+ 	char					call_graph_edge_string[1024];
+ 	int						edge_pos;
+ 	if (call_graph) {
+ 		PgStat_CallGraphEdge **edges = (PgStat_CallGraphEdge **) palloc(hash_get_num_entries(call_graph) * sizeof(PgStat_CallGraphEdge *));;
+ 	
+ 		/* TODO: Build List of OIDs where every second OID is the called OID and every first OID is the caller OID
+ 		 * Example:
+ 		 * Input Hash: 16386->16389, 16389->16391, 16386->16388, 16389->16390
+ 		 * Output Sorted List: [16386,16388,16386,16389,16389,16390,16389,16391]
+ 		*/
+ 		hash_seq_init(&call_graph_stat, call_graph);
+ 		while ((call_graph_edge = (PgStat_CallGraphEdge *) hash_seq_search(&call_graph_stat)) != NULL)
+ 		{
+ 			edges[num_edges] = call_graph_edge;
+ 			num_edges++;
+ 		}
+ 		qsort(edges, num_edges, sizeof(PgStat_CallGraphEdge *), pgstat_edge_comparator);
+ 
+ 		if (!seen_call_graphs)
+ 		{
+ 			/* First time through - initialize seen call graphs hash */
+ 			HASHCTL		hash_ctl;
+ 	
+ 			memset(&hash_ctl, 0, sizeof(hash_ctl));
+ 			seen_call_graphs = hash_create("Seen call graphs",
+ 									PGSTAT_FUNCTION_HASH_SIZE,
+ 									&hash_ctl,
+ 									0);
+ 		}
+ 
+ 		if (num_edges > 0) {
+ 			call_graph_string[0] = '\0';
+ 			for (edge_pos = 0; edge_pos < num_edges; edge_pos++) {
+ 				sprintf(call_graph_edge_string,"%u->%u;",edges[edge_pos]->caller_oid, edges[edge_pos]->called_oid);
+ 				if (strlen(call_graph_edge_string) + strlen(call_graph_string) < 16300) {
+ 					strcat(call_graph_string, call_graph_edge_string);
+ 				}
+ 			}
+ 			call_graph_string[strlen(call_graph_string)-1] = '\0';
+ 			hash_search(seen_call_graphs, call_graph_string, HASH_ENTER, &found);
+ 			if (!found) {
+ 				ereport(LOG, (errmsg("digraph {%s}", call_graph_string)));
+ 			}
+ 		}
+ 	}
+ 	
+ 
  	/*
  	 * Count transaction commit or abort.  (We use counters, not just bools,
  	 * in case the reporting message isn't sent right away.)
***************
*** 1830,1835 **** AtEOXact_PgStat(bool isCommit)
--- 1926,1933 ----
  	}
  	pgStatXactStack = NULL;
  
+ 
+ 
  	/* Make sure any stats snapshot is thrown away */
  	pgstat_clear_snapshot();
  }
***************
*** 3946,3951 **** pgstat_clear_snapshot(void)
--- 4044,4051 ----
  	pgStatDBHash = NULL;
  	localBackendStatusTable = NULL;
  	localNumBackends = 0;
+ 	call_stack = NIL;
+ 	call_graph = NULL;
  }
  
  
***************
*** 4481,4483 **** pgstat_recv_funcpurge(PgStat_MsgFuncpurge *msg, int len)
--- 4581,4616 ----
  						   HASH_REMOVE, NULL);
  	}
  }
+ 
+ /* ----------
+  * pgstat_edge_comparator() -
+  *
+  *	QSort comparator function to compare PgStat_CallGraphEdge structs.
+  * ----------
+  */
+ static int
+ pgstat_edge_comparator(const void *arg1, const void *arg2)
+ {
+ 	PgStat_CallGraphEdge *edge1 = (PgStat_CallGraphEdge *) arg1;
+ 	PgStat_CallGraphEdge *edge2 = (PgStat_CallGraphEdge *) arg2;
+ 
+ 	if (edge1->caller_oid < edge2->caller_oid)
+ 	{
+ 		return 1;
+ 	}
+ 	else if (edge1->caller_oid > edge2->caller_oid)
+ 	{
+ 		return -1;
+ 	}
+ 
+ 	if (edge1->called_oid < edge2->called_oid)
+ 	{
+ 		return 1;
+ 	}
+ 	else if (edge1->called_oid > edge2->called_oid)
+ 	{
+ 		return -1;
+ 	}
+ 
+ 	return 0;
+ }
*** a/src/include/pgstat.h
--- b/src/include/pgstat.h
***************
*** 655,660 **** typedef struct PgStat_FunctionCallUsage
--- 655,668 ----
  	instr_time	f_start;
  } PgStat_FunctionCallUsage;
  
+ /*
+  * Call graph edge of caller and called function oids
+  */
+ typedef struct PgStat_CallGraphEdge
+ {
+ 	Oid	caller_oid;
+ 	Oid	called_oid;
+ } PgStat_CallGraphEdge;
  
  /* ----------
   * GUC parameters