Log memory usage in the dpnode if #define LOG_MEM is set

It turns out each DP uses about 338 bytes of memory.

dpnode.cc

@@ -11,6 +11,9 @@ extern "C" {
 
 #include <set>
 #include <map>
+#ifdef LOG_MEM
+#include <stdio.h>
+#endif
 #include <stdlib.h>
 #include <string.h>
 #include <errno.h>
@@ -44,6 +47,51 @@ static struct DPControllerState {
 			    listener(NULL) {}
 } dpctrlstate;
 
+#ifdef LOG_MEM
+
+/* Log the amount of memory used by the process.  It turns out each DP
+   consumes about 338 bytes of heap.  Also, memory is not deallocated when
+   the table is cleared. */
+static void logmemusage(const char *label)
+{
+    FILE *smaps;
+    FILE *logoutput;
+
+    char logfilename[256];
+
+    sprintf(logfilename, "mem-%05d", getpid());
+
+    smaps = fopen("/proc/self/smaps", "r");
+    if (!smaps) return;
+    logoutput = fopen(logfilename, "a");
+    if (!logoutput) {
+	fclose(smaps);
+	return;
+    }
+    char *line = NULL;
+    size_t n = 0;
+    while(getline(&line, &n, smaps) > -1) {
+	if (!strstr(line, "[heap]")) {
+	    free(line);
+	    line = NULL;
+	    continue;
+	}
+	// Read and parse the next line
+	if (getline(&line, &n, smaps) > -1 && !strncmp(line, "Size:", 5)) {
+	    unsigned long usage;
+	    if (sscanf(line+5, "%lu", &usage) == 1) {
+		fprintf(logoutput, "%s %lu %lu %lu\n", label,
+		    dpctrlstate.table.size(), dpctrlstate.table.max_size(),
+		    usage);
+		break;
+	    }
+	}
+    }
+    fclose(logoutput);
+    fclose(smaps);
+}
+#endif
+
 static void dpnode_event_cb(struct bufferevent *bev, short events,
     void *ctx)
 {
@@ -88,6 +136,11 @@ static void dpnode_reader(struct bufferevent *bev, void *ctx)
 	pair<ZZ,ZZ> ab(zz_a,zz_b);
 	pair<DTable::iterator, bool> res =
 		dpctrlstate.table.insert(DTable::value_type(x,ab));
+#ifdef LOG_MEM
+	if (dpctrlstate.table.size() % 1000 == 0) {
+	    logmemusage("insert");
+	}
+#endif
 
 	if (!res.second) {
 	    const ZZ& order = dpctrlstate.current_problem->order;
@@ -181,7 +234,13 @@ static void stop_problem(void)
 	bufferevent_free(*wit);
     }
     dpctrlstate.workers.clear();
+#ifdef LOG_MEM
+    logmemusage("preclear");
+#endif
     dpctrlstate.table.clear();
+#ifdef LOG_MEM
+    logmemusage("postclear");
+#endif
     dpctrlstate.numdps = 0;
 }