Test JSON output of malloc_stats_print() and fix bugs.

Implement and test a JSON validation parser.  Use the parser to validate
JSON output from malloc_stats_print(), with a significant subset of
supported output options.

This resolves #551.

Makefile.in

@@ -190,6 +190,7 @@ TESTS_UNIT := \
 	$(srcroot)test/unit/slab.c \
 	$(srcroot)test/unit/smoothstep.c \
 	$(srcroot)test/unit/stats.c \
+	$(srcroot)test/unit/stats_print.c \
 	$(srcroot)test/unit/ticker.c \
 	$(srcroot)test/unit/nstime.c \
 	$(srcroot)test/unit/tsd.c \

src/stats.c

@@ -37,7 +37,7 @@ stats_arena_bins_print(void (*write_cb)(void *, const char *), void *cbopaque,
     bool json, bool large, unsigned i)
 {
 	size_t page;
-	bool config_tcache, in_gap, in_gap_prev;
+	bool in_gap, in_gap_prev;
 	unsigned nbins, j;
 
 	CTL_GET("arenas.page", &page, size_t);
@@ -47,7 +47,6 @@ stats_arena_bins_print(void (*write_cb)(void *, const char *), void *cbopaque,
 		malloc_cprintf(write_cb, cbopaque,
 		    "\t\t\t\t\"bins\": [\n");
 	} else {
-		CTL_GET("config.tcache", &config_tcache, bool);
 		if (config_tcache) {
 			malloc_cprintf(write_cb, cbopaque,
 			    "bins:           size ind    allocated      nmalloc"
@@ -700,9 +699,11 @@ stats_general_print(void (*write_cb)(void *, const char *), void *cbopaque,
 		malloc_cprintf(write_cb, cbopaque,
 		    "\t\t\t\"nbins\": %u,\n", nbins);
 
+		if (config_tcache) {
 			CTL_GET("arenas.nhbins", &uv, unsigned);
 			malloc_cprintf(write_cb, cbopaque,
 			    "\t\t\t\"nhbins\": %u,\n", uv);
+		}
 
 		malloc_cprintf(write_cb, cbopaque,
 		    "\t\t\t\"bin\": [\n");
@@ -867,8 +868,10 @@ stats_print_helper(void (*write_cb)(void *, const char *), void *cbopaque,
 				    MALLCTL_ARENAS_ALL, bins, large);
 				if (json) {
 					malloc_cprintf(write_cb, cbopaque,
-					    "\t\t\t}%s\n", (ninitialized > 1) ?
+					    "\t\t\t}%s\n",
-					    "," : "");
+					    ((destroyed_initialized &&
+					    destroyed) || unmerged) ?  "," :
+					    "");
 				}
 			}
 
@@ -886,31 +889,37 @@ stats_print_helper(void (*write_cb)(void *, const char *), void *cbopaque,
 				    MALLCTL_ARENAS_DESTROYED, bins, large);
 				if (json) {
 					malloc_cprintf(write_cb, cbopaque,
-					    "\t\t\t}%s\n", (ninitialized > 1) ?
+					    "\t\t\t}%s\n", unmerged ?  "," :
-					    "," : "");
+					    "");
 				}
 			}
 
 			/* Unmerged stats. */
+			if (unmerged) {
 				for (i = j = 0; i < narenas; i++) {
 					if (initialized[i]) {
 						if (json) {
 							j++;
 							malloc_cprintf(write_cb,
 							    cbopaque,
-						    "\t\t\t\"%u\": {\n", i);
+							    "\t\t\t\"%u\": {\n",
+							    i);
 						} else {
 							malloc_cprintf(write_cb,
-						    cbopaque, "\narenas[%u]:\n",
+							    cbopaque,
+							    "\narenas[%u]:\n",
 							    i);
 						}
-					stats_arena_print(write_cb, cbopaque,
+						stats_arena_print(write_cb,
-					    json, i, bins, large);
+						    cbopaque, json, i, bins,
+						    large);
 						if (json) {
 							malloc_cprintf(write_cb,
 							    cbopaque,
 							    "\t\t\t}%s\n", (j <
-						    ninitialized) ? "," : "");
+							    ninitialized) ? ","
+							    : "");
+						}
 					}
 				}
 			}