Small refactoring of emitter

- Make API more clear for using as standalone json emitter
- Support cases that weren't possible before, e.g.
	- emitting primitive values in an array
	- emitting nested arrays

include/jemalloc/internal/emitter.h

@@ -60,17 +60,6 @@ struct emitter_row_s {
 	ql_head(emitter_col_t) cols;
 };
 
-static inline void
-emitter_row_init(emitter_row_t *row) {
-	ql_new(&row->cols);
-}
-
-static inline void
-emitter_col_init(emitter_col_t *col, emitter_row_t *row) {
-	ql_elm_new(col, link);
-	ql_tail_insert(&row->cols, col, link);
-}
-
 typedef struct emitter_s emitter_t;
 struct emitter_s {
 	emitter_output_t output;
@@ -80,18 +69,10 @@ struct emitter_s {
 	int nesting_depth;
 	/* True if we've already emitted a value at the given depth. */
 	bool item_at_depth;
+	/* True if we emitted a key and will emit corresponding value next. */
+	bool emitted_key;
 };
 
-static inline void
-emitter_init(emitter_t *emitter, emitter_output_t emitter_output,
-    void (*write_cb)(void *, const char *), void *cbopaque) {
-	emitter->output = emitter_output;
-	emitter->write_cb = write_cb;
-	emitter->cbopaque = cbopaque;
-	emitter->item_at_depth = false;
-	emitter->nesting_depth = 0;
-}
-
 /* Internal convenience function.  Write to the emitter the given string. */
 JEMALLOC_FORMAT_PRINTF(2, 3)
 static inline void
@@ -103,18 +84,6 @@ emitter_printf(emitter_t *emitter, const char *format, ...) {
 	va_end(ap);
 }
 
-/* Write to the emitter the given string, but only in table mode. */
-JEMALLOC_FORMAT_PRINTF(2, 3)
-static inline void
-emitter_table_printf(emitter_t *emitter, const char *format, ...) {
-	if (emitter->output == emitter_output_table) {
-		va_list ap;
-		va_start(ap, format);
-		malloc_vcprintf(emitter->write_cb, emitter->cbopaque, format, ap);
-		va_end(ap);
-	}
-}
-
 static inline void
 emitter_gen_fmt(char *out_fmt, size_t out_size, const char *fmt_specifier,
     emitter_justify_t justify, int width) {
@@ -235,47 +204,143 @@ emitter_indent(emitter_t *emitter) {
 
 static inline void
 emitter_json_key_prefix(emitter_t *emitter) {
+	if (emitter->emitted_key) {
+		emitter->emitted_key = false;
+		return;
+	}
 	emitter_printf(emitter, "%s\n", emitter->item_at_depth ? "," : "");
 	emitter_indent(emitter);
 }
 
-static inline void
+/******************************************************************************/
-emitter_begin(emitter_t *emitter) {
+/* Public functions for emitter_t. */
-	if (emitter->output == emitter_output_json) {
-		assert(emitter->nesting_depth == 0);
-		emitter_printf(emitter, "{");
-		emitter_nest_inc(emitter);
-	} else {
-		// tabular init
-		emitter_printf(emitter, "%s", "");
-	}
-}
 
 static inline void
-emitter_end(emitter_t *emitter) {
+emitter_init(emitter_t *emitter, emitter_output_t emitter_output,
-	if (emitter->output == emitter_output_json) {
+    void (*write_cb)(void *, const char *), void *cbopaque) {
-		assert(emitter->nesting_depth == 1);
+	emitter->output = emitter_output;
-		emitter_nest_dec(emitter);
+	emitter->write_cb = write_cb;
-		emitter_printf(emitter, "\n}\n");
+	emitter->cbopaque = cbopaque;
-	}
+	emitter->item_at_depth = false;
+	emitter->emitted_key = false; 
+	emitter->nesting_depth = 0;
 }
 
+/******************************************************************************/
+/* JSON public API. */
+
 /* 
- * Note emits a different kv pair as well, but only in table mode.  Omits the
+ * Emits a key (e.g. as appears in an object). The next json entity emitted will
- * note if table_note_key is NULL.
+ * be the corresponding value.
  */
 static inline void
-emitter_kv_note(emitter_t *emitter, const char *json_key, const char *table_key,
+emitter_json_key(emitter_t *emitter, const char *json_key) {
+	if (emitter->output == emitter_output_json) {
+		emitter_json_key_prefix(emitter);
+		emitter_printf(emitter, "\"%s\": ", json_key);
+		emitter->emitted_key = true;
+	}
+}
+
+static inline void
+emitter_json_value(emitter_t *emitter, emitter_type_t value_type,
+    const void *value) {
+	if (emitter->output == emitter_output_json) {
+		emitter_json_key_prefix(emitter);
+		emitter_print_value(emitter, emitter_justify_none, -1,
+		    value_type, value);
+		emitter->item_at_depth = true;
+	}
+}
+
+/* Shorthand for calling emitter_json_key and then emitter_json_value. */
+static inline void
+emitter_json_kv(emitter_t *emitter, const char *json_key,
+    emitter_type_t value_type, const void *value) {
+	emitter_json_key(emitter, json_key);
+	emitter_json_value(emitter, value_type, value);
+}
+
+static inline void
+emitter_json_array_begin(emitter_t *emitter) {
+	if (emitter->output == emitter_output_json) {
+		emitter_json_key_prefix(emitter);
+		emitter_printf(emitter, "[");
+		emitter_nest_inc(emitter);
+	}
+}
+
+/* Shorthand for calling emitter_json_key and then emitter_json_array_begin. */
+static inline void
+emitter_json_array_kv_begin(emitter_t *emitter, const char *json_key) {
+	emitter_json_key(emitter, json_key);
+	emitter_json_array_begin(emitter);
+}
+
+static inline void
+emitter_json_array_end(emitter_t *emitter) {
+	if (emitter->output == emitter_output_json) {
+		assert(emitter->nesting_depth > 0);
+		emitter_nest_dec(emitter);
+		emitter_printf(emitter, "\n");
+		emitter_indent(emitter);
+		emitter_printf(emitter, "]");
+	}
+}
+
+static inline void
+emitter_json_object_begin(emitter_t *emitter) {
+	if (emitter->output == emitter_output_json) {
+		emitter_json_key_prefix(emitter);
+		emitter_printf(emitter, "{");
+		emitter_nest_inc(emitter);
+	}
+}
+
+/* Shorthand for calling emitter_json_key and then emitter_json_object_begin. */
+static inline void
+emitter_json_object_kv_begin(emitter_t *emitter, const char *json_key) {
+	emitter_json_key(emitter, json_key);
+	emitter_json_object_begin(emitter);
+}
+
+static inline void
+emitter_json_object_end(emitter_t *emitter) {
+	if (emitter->output == emitter_output_json) {
+		assert(emitter->nesting_depth > 0);
+		emitter_nest_dec(emitter);
+		emitter_printf(emitter, "\n");
+		emitter_indent(emitter);
+		emitter_printf(emitter, "}");
+	}
+}
+
+
+/******************************************************************************/
+/* Table public API. */
+
+static inline void
+emitter_table_dict_begin(emitter_t *emitter, const char *table_key) {
+	if (emitter->output == emitter_output_table) {
+		emitter_indent(emitter);
+		emitter_printf(emitter, "%s\n", table_key);
+		emitter_nest_inc(emitter);
+	}
+}
+
+static inline void
+emitter_table_dict_end(emitter_t *emitter) {
+	if (emitter->output == emitter_output_table) {
+		emitter_nest_dec(emitter);
+	}
+}
+
+static inline void
+emitter_table_kv_note(emitter_t *emitter, const char *table_key,
     emitter_type_t value_type, const void *value,
     const char *table_note_key, emitter_type_t table_note_value_type,
     const void *table_note_value) {
-	if (emitter->output == emitter_output_json) {
+	if (emitter->output == emitter_output_table) {
-		assert(emitter->nesting_depth > 0);
-		emitter_json_key_prefix(emitter);
-		emitter_printf(emitter, "\"%s\": ", json_key);
-		emitter_print_value(emitter, emitter_justify_none, -1,
-		    value_type, value);
-	} else {
 		emitter_indent(emitter);
 		emitter_printf(emitter, "%s: ", table_key);
 		emitter_print_value(emitter, emitter_justify_none, -1,
@@ -292,130 +357,22 @@ emitter_kv_note(emitter_t *emitter, const char *json_key, const char *table_key,
 }
 
 static inline void
-emitter_kv(emitter_t *emitter, const char *json_key, const char *table_key,
+emitter_table_kv(emitter_t *emitter, const char *table_key,
     emitter_type_t value_type, const void *value) {
-	emitter_kv_note(emitter, json_key, table_key, value_type, value, NULL,
+	emitter_table_kv_note(emitter, table_key, value_type, value, NULL,
 	    emitter_type_bool, NULL);
 }
 
-static inline void
-emitter_json_kv(emitter_t *emitter, const char *json_key,
-    emitter_type_t value_type, const void *value) {
-	if (emitter->output == emitter_output_json) {
-		emitter_kv(emitter, json_key, NULL, value_type, value);
-	}
-}
 
+/* Write to the emitter the given string, but only in table mode. */
+JEMALLOC_FORMAT_PRINTF(2, 3)
 static inline void
-emitter_table_kv(emitter_t *emitter, const char *table_key,
+emitter_table_printf(emitter_t *emitter, const char *format, ...) {
-    emitter_type_t value_type, const void *value) {
 	if (emitter->output == emitter_output_table) {
-		emitter_kv(emitter, NULL, table_key, value_type, value);
+		va_list ap;
-	}
+		va_start(ap, format);
-}
+		malloc_vcprintf(emitter->write_cb, emitter->cbopaque, format, ap);
-
+		va_end(ap);
-static inline void
-emitter_dict_begin(emitter_t *emitter, const char *json_key,
-    const char *table_header) {
-	if (emitter->output == emitter_output_json) {
-		emitter_json_key_prefix(emitter);
-		emitter_printf(emitter, "\"%s\": {", json_key);
-		emitter_nest_inc(emitter);
-	} else {
-		emitter_indent(emitter);
-		emitter_printf(emitter, "%s\n", table_header);
-		emitter_nest_inc(emitter);
-	}
-}
-
-static inline void
-emitter_dict_end(emitter_t *emitter) {
-	if (emitter->output == emitter_output_json) {
-		assert(emitter->nesting_depth > 0);
-		emitter_nest_dec(emitter);
-		emitter_printf(emitter, "\n");
-		emitter_indent(emitter);
-		emitter_printf(emitter, "}");
-	} else {
-		emitter_nest_dec(emitter);
-	}
-}
-
-static inline void
-emitter_json_dict_begin(emitter_t *emitter, const char *json_key) {
-	if (emitter->output == emitter_output_json) {
-		emitter_dict_begin(emitter, json_key, NULL);
-	}
-}
-
-static inline void
-emitter_json_dict_end(emitter_t *emitter) {
-	if (emitter->output == emitter_output_json) {
-		emitter_dict_end(emitter);
-	}
-}
-
-static inline void
-emitter_table_dict_begin(emitter_t *emitter, const char *table_key) {
-	if (emitter->output == emitter_output_table) {
-		emitter_dict_begin(emitter, NULL, table_key);
-	}
-}
-
-static inline void
-emitter_table_dict_end(emitter_t *emitter) {
-	if (emitter->output == emitter_output_table) {
-		emitter_dict_end(emitter);
-	}
-}
-
-static inline void
-emitter_json_arr_begin(emitter_t *emitter, const char *json_key) {
-	if (emitter->output == emitter_output_json) {
-		emitter_json_key_prefix(emitter);
-		emitter_printf(emitter, "\"%s\": [", json_key);
-		emitter_nest_inc(emitter);
-	}
-}
-
-static inline void
-emitter_json_arr_end(emitter_t *emitter) {
-	if (emitter->output == emitter_output_json) {
-		assert(emitter->nesting_depth > 0);
-		emitter_nest_dec(emitter);
-		emitter_printf(emitter, "\n");
-		emitter_indent(emitter);
-		emitter_printf(emitter, "]");
-	}
-}
-
-static inline void
-emitter_json_arr_obj_begin(emitter_t *emitter) {
-	if (emitter->output == emitter_output_json) {
-		emitter_json_key_prefix(emitter);
-		emitter_printf(emitter, "{");
-		emitter_nest_inc(emitter);
-	}
-}
-
-static inline void
-emitter_json_arr_obj_end(emitter_t *emitter) {
-	if (emitter->output == emitter_output_json) {
-		assert(emitter->nesting_depth > 0);
-		emitter_nest_dec(emitter);
-		emitter_printf(emitter, "\n");
-		emitter_indent(emitter);
-		emitter_printf(emitter, "}");
-	}
-}
-
-static inline void
-emitter_json_arr_value(emitter_t *emitter, emitter_type_t value_type,
-    const void *value) {
-	if (emitter->output == emitter_output_json) {
-		emitter_json_key_prefix(emitter);
-		emitter_print_value(emitter, emitter_justify_none, -1,
-		    value_type, value);
 	}
 }
 
@@ -432,4 +389,93 @@ emitter_table_row(emitter_t *emitter, emitter_row_t *row) {
 	emitter_table_printf(emitter, "\n");
 }
 
+static inline void
+emitter_row_init(emitter_row_t *row) {
+	ql_new(&row->cols);
+}
+
+static inline void
+emitter_col_init(emitter_col_t *col, emitter_row_t *row) {
+	ql_elm_new(col, link);
+	ql_tail_insert(&row->cols, col, link);
+}
+
+
+/******************************************************************************/
+/*
+ * Generalized public API. Emits using either JSON or table, according to
+ * settings in the emitter_t. */
+
+/*
+ * Note emits a different kv pair as well, but only in table mode.  Omits the
+ * note if table_note_key is NULL.
+ */
+static inline void
+emitter_kv_note(emitter_t *emitter, const char *json_key, const char *table_key,
+    emitter_type_t value_type, const void *value,
+    const char *table_note_key, emitter_type_t table_note_value_type,
+    const void *table_note_value) {
+	if (emitter->output == emitter_output_json) {
+		emitter_json_key(emitter, json_key);
+		emitter_json_value(emitter, value_type, value);
+	} else {
+		emitter_table_kv_note(emitter, table_key, value_type, value,
+		    table_note_key, table_note_value_type, table_note_value);
+	}
+	emitter->item_at_depth = true;
+}
+
+static inline void
+emitter_kv(emitter_t *emitter, const char *json_key, const char *table_key,
+    emitter_type_t value_type, const void *value) {
+	emitter_kv_note(emitter, json_key, table_key, value_type, value, NULL,
+	    emitter_type_bool, NULL);
+}
+
+static inline void
+emitter_dict_begin(emitter_t *emitter, const char *json_key,
+    const char *table_header) {
+	if (emitter->output == emitter_output_json) {
+		emitter_json_key(emitter, json_key);
+		emitter_json_object_begin(emitter);
+	} else {
+		emitter_table_dict_begin(emitter, table_header);
+	}
+}
+
+static inline void
+emitter_dict_end(emitter_t *emitter) {
+	if (emitter->output == emitter_output_json) {
+		emitter_json_object_end(emitter);
+	} else {
+		emitter_table_dict_end(emitter);
+	}
+}
+
+static inline void
+emitter_begin(emitter_t *emitter) {
+	if (emitter->output == emitter_output_json) {
+		assert(emitter->nesting_depth == 0);
+		emitter_printf(emitter, "{");
+		emitter_nest_inc(emitter);
+	} else {
+		/*
+		 * This guarantees that we always call write_cb at least once.
+		 * This is useful if some invariant is established by each call
+		 * to write_cb, but doesn't hold initially: e.g., some buffer
+		 * holds a null-terminated string.
+		 */
+		emitter_printf(emitter, "%s", "");
+	}
+}
+
+static inline void
+emitter_end(emitter_t *emitter) {
+	if (emitter->output == emitter_output_json) {
+		assert(emitter->nesting_depth == 1);
+		emitter_nest_dec(emitter);
+		emitter_printf(emitter, "\n}\n");
+	}
+}
+
 #endif /* JEMALLOC_INTERNAL_EMITTER_H */

src/stats.c

@@ -287,7 +287,7 @@ stats_arena_bins_print(emitter_t *emitter, bool mutex, unsigned i) {
 	header_col_size.width -=5;
 	emitter_table_printf(emitter, "bins:");
 	emitter_table_row(emitter, &header_row);
-	emitter_json_arr_begin(emitter, "bins");
+	emitter_json_array_kv_begin(emitter, "bins");
 
 	for (j = 0, in_gap = false; j < nbins; j++) {
 		uint64_t nslabs;
@@ -333,7 +333,7 @@ stats_arena_bins_print(emitter_t *emitter, bool mutex, unsigned i) {
 			    col_mutex32);
 		}
 
-		emitter_json_arr_obj_begin(emitter);
+		emitter_json_object_begin(emitter);
 		emitter_json_kv(emitter, "nmalloc", emitter_type_uint64,
 		    &nmalloc);
 		emitter_json_kv(emitter, "ndalloc", emitter_type_uint64,
@@ -351,12 +351,12 @@ stats_arena_bins_print(emitter_t *emitter, bool mutex, unsigned i) {
 		emitter_json_kv(emitter, "curslabs", emitter_type_size,
 		    &curslabs);
 		if (mutex) {
-			emitter_json_dict_begin(emitter, "mutex");
+			emitter_json_object_kv_begin(emitter, "mutex");
 			mutex_stats_emit(emitter, NULL, col_mutex64,
 			    col_mutex32);
-			emitter_json_dict_end(emitter);
+			emitter_json_object_end(emitter);
 		}
-		emitter_json_arr_obj_end(emitter);
+		emitter_json_object_end(emitter);
 
 		size_t availregs = nregs * curslabs;
 		char util[6];
@@ -400,7 +400,7 @@ stats_arena_bins_print(emitter_t *emitter, bool mutex, unsigned i) {
 
 		emitter_table_row(emitter, &row);
 	}
-	emitter_json_arr_end(emitter); /* Close "bins". */
+	emitter_json_array_end(emitter); /* Close "bins". */
 
 	if (in_gap) {
 		emitter_table_printf(emitter, "                     ---\n");
@@ -447,7 +447,7 @@ stats_arena_lextents_print(emitter_t *emitter, unsigned i) {
 	header_size.width -= 6;
 	emitter_table_printf(emitter, "large:");
 	emitter_table_row(emitter, &header_row);
-	emitter_json_arr_begin(emitter, "lextents");
+	emitter_json_array_kv_begin(emitter, "lextents");
 
 	for (j = 0, in_gap = false; j < nlextents; j++) {
 		uint64_t nmalloc, ndalloc, nrequests;
@@ -471,10 +471,10 @@ stats_arena_lextents_print(emitter_t *emitter, unsigned i) {
 		CTL_M2_M4_GET("stats.arenas.0.lextents.0.curlextents", i, j,
 		    &curlextents, size_t);
 
-		emitter_json_arr_obj_begin(emitter);
+		emitter_json_object_begin(emitter);
 		emitter_json_kv(emitter, "curlextents", emitter_type_size,
 		    &curlextents);
-		emitter_json_arr_obj_end(emitter);
+		emitter_json_object_end(emitter);
 
 		col_size.size_val = lextent_size;
 		col_ind.unsigned_val = nbins + j;
@@ -488,7 +488,7 @@ stats_arena_lextents_print(emitter_t *emitter, unsigned i) {
 			emitter_table_row(emitter, &row);
 		}
 	}
-	emitter_json_arr_end(emitter); /* Close "lextents". */
+	emitter_json_array_end(emitter); /* Close "lextents". */
 	if (in_gap) {
 		emitter_table_printf(emitter, "                     ---\n");
 	}
@@ -504,19 +504,19 @@ stats_arena_mutexes_print(emitter_t *emitter, unsigned arena_ind) {
 	emitter_row_init(&row);
 	mutex_stats_init_cols(&row, "", &col_name, col64, col32);
 
-	emitter_json_dict_begin(emitter, "mutexes");
+	emitter_json_object_kv_begin(emitter, "mutexes");
 	emitter_table_row(emitter, &row);
 
 	for (mutex_prof_arena_ind_t i = 0; i < mutex_prof_num_arena_mutexes;
 	    i++) {
 		const char *name = arena_mutex_names[i];
-		emitter_json_dict_begin(emitter, name);
+		emitter_json_object_kv_begin(emitter, name);
 		mutex_stats_read_arena(arena_ind, i, name, &col_name, col64,
 		    col32);
 		mutex_stats_emit(emitter, &row, col64, col32);
-		emitter_json_dict_end(emitter); /* Close the mutex dict. */
+		emitter_json_object_end(emitter); /* Close the mutex dict. */
 	}
-	emitter_json_dict_end(emitter); /* End "mutexes". */
+	emitter_json_object_end(emitter); /* End "mutexes". */
 }
 
 static void
@@ -738,7 +738,7 @@ stats_arena_print(emitter_t *emitter, unsigned i, bool bins, bool large,
 	alloc_count_##name.type = emitter_type_##valtype;		\
 	alloc_count_##name.valtype##_val = small_or_large##_##name;
 
-	emitter_json_dict_begin(emitter, "small");
+	emitter_json_object_kv_begin(emitter, "small");
 	alloc_count_title.str_val = "small:";
 
 	GET_AND_EMIT_ALLOC_STAT(small, allocated, size)
@@ -747,9 +747,9 @@ stats_arena_print(emitter_t *emitter, unsigned i, bool bins, bool large,
 	GET_AND_EMIT_ALLOC_STAT(small, nrequests, uint64)
 
 	emitter_table_row(emitter, &alloc_count_row);
-	emitter_json_dict_end(emitter); /* Close "small". */
+	emitter_json_object_end(emitter); /* Close "small". */
 
-	emitter_json_dict_begin(emitter, "large");
+	emitter_json_object_kv_begin(emitter, "large");
 	alloc_count_title.str_val = "large:";
 
 	GET_AND_EMIT_ALLOC_STAT(large, allocated, size)
@@ -758,7 +758,7 @@ stats_arena_print(emitter_t *emitter, unsigned i, bool bins, bool large,
 	GET_AND_EMIT_ALLOC_STAT(large, nrequests, uint64)
 
 	emitter_table_row(emitter, &alloc_count_row);
-	emitter_json_dict_end(emitter); /* Close "large". */
+	emitter_json_object_end(emitter); /* Close "large". */
 
 #undef GET_AND_EMIT_ALLOC_STAT
 
@@ -980,7 +980,7 @@ stats_general_print(emitter_t *emitter) {
 	 * The json output sticks arena info into an "arenas" dict; the table
 	 * output puts them at the top-level.
 	 */
-	emitter_json_dict_begin(emitter, "arenas");
+	emitter_json_object_kv_begin(emitter, "arenas");
 
 	CTL_GET("arenas.narenas", &uv, unsigned);
 	emitter_kv(emitter, "narenas", "Arenas", emitter_type_unsigned, &uv);
@@ -1021,9 +1021,9 @@ stats_general_print(emitter_t *emitter) {
 	 * (not just omit the printing).
 	 */
 	if (emitter->output == emitter_output_json) {
-		emitter_json_arr_begin(emitter, "bin");
+		emitter_json_array_kv_begin(emitter, "bin");
 		for (unsigned i = 0; i < nbins; i++) {
-			emitter_json_arr_obj_begin(emitter);
+			emitter_json_object_begin(emitter);
 
 			CTL_M2_GET("arenas.bin.0.size", i, &sv, size_t);
 			emitter_json_kv(emitter, "size", emitter_type_size,
@@ -1037,9 +1037,9 @@ stats_general_print(emitter_t *emitter) {
 			emitter_json_kv(emitter, "slab_size", emitter_type_size,
 			    &sv);
 
-			emitter_json_arr_obj_end(emitter);
+			emitter_json_object_end(emitter);
 		}
-		emitter_json_arr_end(emitter); /* Close "bin". */
+		emitter_json_array_end(emitter); /* Close "bin". */
 	}
 
 	unsigned nlextents;
@@ -1048,20 +1048,20 @@ stats_general_print(emitter_t *emitter) {
 	    emitter_type_unsigned, &nlextents);
 
 	if (emitter->output == emitter_output_json) {
-		emitter_json_arr_begin(emitter, "lextent");
+		emitter_json_array_kv_begin(emitter, "lextent");
 		for (unsigned i = 0; i < nlextents; i++) {
-			emitter_json_arr_obj_begin(emitter);
+			emitter_json_object_begin(emitter);
 
 			CTL_M2_GET("arenas.lextent.0.size", i, &sv, size_t);
 			emitter_json_kv(emitter, "size", emitter_type_size,
 			    &sv);
 
-			emitter_json_arr_obj_end(emitter);
+			emitter_json_object_end(emitter);
 		}
-		emitter_json_arr_end(emitter); /* Close "lextent". */
+		emitter_json_array_end(emitter); /* Close "lextent". */
 	}
 
-	emitter_json_dict_end(emitter); /* Close "arenas" */
+	emitter_json_object_end(emitter); /* Close "arenas" */
 }
 
 static void
@@ -1098,7 +1098,7 @@ stats_print_helper(emitter_t *emitter, bool merged, bool destroyed,
 	}
 
 	/* Generic global stats. */
-	emitter_json_dict_begin(emitter, "stats");
+	emitter_json_object_kv_begin(emitter, "stats");
 	emitter_json_kv(emitter, "allocated", emitter_type_size, &allocated);
 	emitter_json_kv(emitter, "active", emitter_type_size, &active);
 	emitter_json_kv(emitter, "metadata", emitter_type_size, &metadata);
@@ -1114,14 +1114,14 @@ stats_print_helper(emitter_t *emitter, bool merged, bool destroyed,
 	    resident, mapped, retained);
 
 	/* Background thread stats. */
-	emitter_json_dict_begin(emitter, "background_thread");
+	emitter_json_object_kv_begin(emitter, "background_thread");
 	emitter_json_kv(emitter, "num_threads", emitter_type_size,
 	    &num_background_threads);
 	emitter_json_kv(emitter, "num_runs", emitter_type_uint64,
 	    &background_thread_num_runs);
 	emitter_json_kv(emitter, "run_interval", emitter_type_uint64,
 	    &background_thread_run_interval);
-	emitter_json_dict_end(emitter); /* Close "background_thread". */
+	emitter_json_object_end(emitter); /* Close "background_thread". */
 
 	emitter_table_printf(emitter, "Background threads: %zu, "
 	    "num_runs: %"FMTu64", run_interval: %"FMTu64" ns\n",
@@ -1138,25 +1138,25 @@ stats_print_helper(emitter_t *emitter, bool merged, bool destroyed,
 		mutex_stats_init_cols(&row, "", &name, col64, col32);
 
 		emitter_table_row(emitter, &row);
-		emitter_json_dict_begin(emitter, "mutexes");
+		emitter_json_object_kv_begin(emitter, "mutexes");
 
 		for (int i = 0; i < mutex_prof_num_global_mutexes; i++) {
 			mutex_stats_read_global(global_mutex_names[i], &name,
 			    col64, col32);
-			emitter_json_dict_begin(emitter, global_mutex_names[i]);
+			emitter_json_object_kv_begin(emitter, global_mutex_names[i]);
 			mutex_stats_emit(emitter, &row, col64, col32);
-			emitter_json_dict_end(emitter);
+			emitter_json_object_end(emitter);
 		}
 
-		emitter_json_dict_end(emitter); /* Close "mutexes". */
+		emitter_json_object_end(emitter); /* Close "mutexes". */
 	}
 
-	emitter_json_dict_end(emitter); /* Close "stats". */
+	emitter_json_object_end(emitter); /* Close "stats". */
 
 	if (merged || destroyed || unmerged) {
 		unsigned narenas;
 
-		emitter_json_dict_begin(emitter, "stats.arenas");
+		emitter_json_object_kv_begin(emitter, "stats.arenas");
 
 		CTL_GET("arenas.narenas", &narenas, unsigned);
 		size_t mib[3];
@@ -1185,10 +1185,10 @@ stats_print_helper(emitter_t *emitter, bool merged, bool destroyed,
 		if (merged && (ninitialized > 1 || !unmerged)) {
 			/* Print merged arena stats. */
 			emitter_table_printf(emitter, "Merged arenas stats:\n");
-			emitter_json_dict_begin(emitter, "merged");
+			emitter_json_object_kv_begin(emitter, "merged");
 			stats_arena_print(emitter, MALLCTL_ARENAS_ALL, bins,
 			    large, mutex);
-			emitter_json_dict_end(emitter); /* Close "merged". */
+			emitter_json_object_end(emitter); /* Close "merged". */
 		}
 
 		/* Destroyed stats. */
@@ -1196,10 +1196,10 @@ stats_print_helper(emitter_t *emitter, bool merged, bool destroyed,
 			/* Print destroyed arena stats. */
 			emitter_table_printf(emitter,
 			    "Destroyed arenas stats:\n");
-			emitter_json_dict_begin(emitter, "destroyed");
+			emitter_json_object_kv_begin(emitter, "destroyed");
 			stats_arena_print(emitter, MALLCTL_ARENAS_DESTROYED,
 			    bins, large, mutex);
-			emitter_json_dict_end(emitter); /* Close "destroyed". */
+			emitter_json_object_end(emitter); /* Close "destroyed". */
 		}
 
 		/* Unmerged stats. */
@@ -1209,18 +1209,18 @@ stats_print_helper(emitter_t *emitter, bool merged, bool destroyed,
 					char arena_ind_str[20];
 					malloc_snprintf(arena_ind_str,
 					    sizeof(arena_ind_str), "%u", i);
-					emitter_json_dict_begin(emitter,
+					emitter_json_object_kv_begin(emitter,
 					    arena_ind_str);
 					emitter_table_printf(emitter,
 					    "arenas[%s]:\n", arena_ind_str);
 					stats_arena_print(emitter, i, bins,
 					    large, mutex);
 					/* Close "<arena-ind>". */
-					emitter_json_dict_end(emitter);
+					emitter_json_object_end(emitter);
 				}
 			}
 		}
-		emitter_json_dict_end(emitter); /* Close "stats.arenas". */
+		emitter_json_object_end(emitter); /* Close "stats.arenas". */
 	}
 }
 
@@ -1273,7 +1273,7 @@ stats_print(void (*write_cb)(void *, const char *), void *cbopaque,
 	    cbopaque);
 	emitter_begin(&emitter);
 	emitter_table_printf(&emitter, "___ Begin jemalloc statistics ___\n");
-	emitter_json_dict_begin(&emitter, "jemalloc");
+	emitter_json_object_kv_begin(&emitter, "jemalloc");
 
 	if (general) {
 		stats_general_print(&emitter);
@@ -1283,7 +1283,7 @@ stats_print(void (*write_cb)(void *, const char *), void *cbopaque,
 		    bins, large, mutex);
 	}
 
-	emitter_json_dict_end(&emitter); /* Closes the "jemalloc" dict. */
+	emitter_json_object_end(&emitter); /* Closes the "jemalloc" dict. */
 	emitter_table_printf(&emitter, "--- End jemalloc statistics ---\n");
 	emitter_end(&emitter);
 }

test/unit/emitter.c

@@ -169,7 +169,7 @@ static void emit_nested_dict(emitter_t *emitter) {
 	emitter_end(emitter);
 }
 
-static const char *nested_dict_json =
+static const char *nested_object_json =
 "{\n"
 "\t\"json1\": {\n"
 "\t\t\"json2\": {\n"
@@ -183,7 +183,7 @@ static const char *nested_dict_json =
 "\t}\n"
 "}\n";
 
-static const char *nested_dict_table =
+static const char *nested_object_table =
 "Dict 1\n"
 "  Dict 2\n"
 "    A primitive: 123\n"
@@ -192,8 +192,8 @@ static const char *nested_dict_table =
 "  Another primitive: 123\n";
 
 TEST_BEGIN(test_nested_dict) {
-	assert_emit_output(&emit_nested_dict, nested_dict_json,
+	assert_emit_output(&emit_nested_dict, nested_object_json,
-	    nested_dict_table);
+	    nested_object_table);
 }
 TEST_END
 
@@ -256,13 +256,14 @@ emit_modal(emitter_t *emitter) {
 	int val = 123;
 	emitter_begin(emitter);
 	emitter_dict_begin(emitter, "j0", "T0");
-	emitter_json_dict_begin(emitter, "j1");
+	emitter_json_key(emitter, "j1");
+	emitter_json_object_begin(emitter);
 	emitter_kv(emitter, "i1", "I1", emitter_type_int, &val);
 	emitter_json_kv(emitter, "i2", emitter_type_int, &val);
 	emitter_table_kv(emitter, "I3", emitter_type_int, &val);
 	emitter_table_dict_begin(emitter, "T1");
 	emitter_kv(emitter, "i4", "I4", emitter_type_int, &val);
-	emitter_json_dict_end(emitter); /* Close j1 */
+	emitter_json_object_end(emitter); /* Close j1 */
 	emitter_kv(emitter, "i5", "I5", emitter_type_int, &val);
 	emitter_table_dict_end(emitter); /* Close T1 */
 	emitter_kv(emitter, "i6", "I6", emitter_type_int, &val);
@@ -302,24 +303,26 @@ emit_json_arr(emitter_t *emitter) {
 	int ival = 123;
 
 	emitter_begin(emitter);
-	emitter_json_dict_begin(emitter, "dict");
+	emitter_json_key(emitter, "dict");
-	emitter_json_arr_begin(emitter, "arr");
+	emitter_json_object_begin(emitter);
-	emitter_json_arr_obj_begin(emitter);
+	emitter_json_key(emitter, "arr");
+	emitter_json_array_begin(emitter);
+	emitter_json_object_begin(emitter);
 	emitter_json_kv(emitter, "foo", emitter_type_int, &ival);
-	emitter_json_arr_obj_end(emitter); /* Close arr[0] */
+	emitter_json_object_end(emitter); /* Close arr[0] */
 	/* arr[1] and arr[2] are primitives. */
-	emitter_json_arr_value(emitter, emitter_type_int, &ival);
+	emitter_json_value(emitter, emitter_type_int, &ival);
-	emitter_json_arr_value(emitter, emitter_type_int, &ival);
+	emitter_json_value(emitter, emitter_type_int, &ival);
-	emitter_json_arr_obj_begin(emitter);
+	emitter_json_object_begin(emitter);
 	emitter_json_kv(emitter, "bar", emitter_type_int, &ival);
 	emitter_json_kv(emitter, "baz", emitter_type_int, &ival);
-	emitter_json_arr_obj_end(emitter); /* Close arr[3]. */
+	emitter_json_object_end(emitter); /* Close arr[3]. */
-	emitter_json_arr_end(emitter); /* Close arr. */
+	emitter_json_array_end(emitter); /* Close arr. */
-	emitter_json_dict_end(emitter); /* Close dict. */
+	emitter_json_object_end(emitter); /* Close dict. */
 	emitter_end(emitter);
 }
 
-static const char *json_arr_json =
+static const char *json_array_json =
 "{\n"
 "\t\"dict\": {\n"
 "\t\t\"arr\": [\n"
@@ -336,10 +339,62 @@ static const char *json_arr_json =
 "\t}\n"
 "}\n";
 
-static const char *json_arr_table = "";
+static const char *json_array_table = "";
 
 TEST_BEGIN(test_json_arr) {
-	assert_emit_output(&emit_json_arr, json_arr_json, json_arr_table);
+	assert_emit_output(&emit_json_arr, json_array_json, json_array_table);
+}
+TEST_END
+
+static void
+emit_json_nested_array(emitter_t *emitter) {
+	int ival = 123;
+	char *sval = "foo";
+	emitter_begin(emitter);
+	emitter_json_array_begin(emitter);
+		emitter_json_array_begin(emitter);
+		emitter_json_value(emitter, emitter_type_int, &ival);
+		emitter_json_value(emitter, emitter_type_string, &sval);
+		emitter_json_value(emitter, emitter_type_int, &ival);
+		emitter_json_value(emitter, emitter_type_string, &sval);
+		emitter_json_array_end(emitter);
+		emitter_json_array_begin(emitter);
+		emitter_json_value(emitter, emitter_type_int, &ival);
+		emitter_json_array_end(emitter);
+		emitter_json_array_begin(emitter);
+		emitter_json_value(emitter, emitter_type_string, &sval);
+		emitter_json_value(emitter, emitter_type_int, &ival);
+		emitter_json_array_end(emitter);
+		emitter_json_array_begin(emitter);
+		emitter_json_array_end(emitter);
+	emitter_json_array_end(emitter);
+	emitter_end(emitter);
+}
+
+static const char *json_nested_array_json =
+"{\n"
+"\t[\n"
+"\t\t[\n"
+"\t\t\t123,\n"
+"\t\t\t\"foo\",\n"
+"\t\t\t123,\n"
+"\t\t\t\"foo\"\n"
+"\t\t],\n"
+"\t\t[\n"
+"\t\t\t123\n"
+"\t\t],\n"
+"\t\t[\n"
+"\t\t\t\"foo\",\n"
+"\t\t\t123\n"
+"\t\t],\n"
+"\t\t[\n"
+"\t\t]\n"
+"\t]\n"
+"}\n";
+
+TEST_BEGIN(test_json_nested_arr) {
+	assert_emit_output(&emit_json_nested_array, json_nested_array_json,
+	    json_array_table);
 }
 TEST_END
 
@@ -409,5 +464,6 @@ main(void) {
 	    test_types,
 	    test_modal,
 	    test_json_arr,
+	    test_json_nested_arr,
 	    test_table_row);
 }