Introduce the emitter module.

The emitter can be used to produce structured json or tabular output.  For now
it has no uses; in subsequent commits, I'll begin transitioning stats printing
code over.

1 files changed, 381 insertions, 0 deletions

diff --git a/include/jemalloc/internal/emitter.h b/include/jemalloc/internal/emitter.h
new file mode 100644
index 00000000..c82dbdb1
--- /dev/null
+++ b/include/jemalloc/internal/emitter.h
@@ -0,0 +1,381 @@
+#ifndef JEMALLOC_INTERNAL_EMITTER_H
+#define JEMALLOC_INTERNAL_EMITTER_H
+
+typedef enum emitter_output_e emitter_output_t;
+enum emitter_output_e {
+	emitter_output_json,
+	emitter_output_table
+};
+
+typedef enum emitter_justify_e emitter_justify_t;
+enum emitter_justify_e {
+	emitter_justify_left,
+	emitter_justify_right,
+	/* Not for users; just to pass to internal functions. */
+	emitter_justify_none
+};
+
+typedef enum emitter_type_e emitter_type_t;
+enum emitter_type_e {
+	emitter_type_bool,
+	emitter_type_int,
+	emitter_type_unsigned,
+	emitter_type_uint32,
+	emitter_type_uint64,
+	emitter_type_size,
+	emitter_type_ssize,
+	emitter_type_string,
+};
+
+typedef struct emitter_s emitter_t;
+struct emitter_s {
+	emitter_output_t output;
+	/* The output information. */
+	void (*write_cb)(void *, const char *);
+	void *cbopaque;
+	int nesting_depth;
+	/* True if we've already emitted a value at the given depth. */
+	bool item_at_depth;
+};
+
+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
+emitter_printf(emitter_t *emitter, const char *format, ...) {
+	va_list ap;
+
+	va_start(ap, format);
+	malloc_vcprintf(emitter->write_cb, emitter->cbopaque, format, ap);
+	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) {
+	size_t written;
+	if (justify == emitter_justify_none) {
+		written = malloc_snprintf(out_fmt, out_size,
+		    "%%%s", fmt_specifier);
+	} else if (justify == emitter_justify_left) {
+		written = malloc_snprintf(out_fmt, out_size,
+		    "%%-%d%s", width, fmt_specifier);
+	} else {
+		written = malloc_snprintf(out_fmt, out_size,
+		    "%%%d%s", width, fmt_specifier);
+	}
+	/* Only happens in case of bad format string, which *we* choose. */
+	assert(written <  out_size);
+}
+
+/*
+ * Internal.  Emit the given value type in the relevant encoding (so that the
+ * bool true gets mapped to json "true", but the string "true" gets mapped to
+ * json "\"true\"", for instance.
+ *
+ * Width is ignored if justify is emitter_justify_none.
+ */
+static inline void
+emitter_print_value(emitter_t *emitter, emitter_justify_t justify, int width,
+    emitter_type_t value_type, const void *value) {
+	size_t str_written;
+#define BUF_SIZE 256
+#define FMT_SIZE 10
+	/*
+	 * We dynamically generate a format string to emit, to let us use the
+	 * snprintf machinery.  This is kinda hacky, but gets the job done
+	 * quickly without having to think about the various snprintf edge
+	 * cases.
+	 */
+	char fmt[FMT_SIZE];
+	char buf[BUF_SIZE];
+
+#define EMIT_SIMPLE(type, format)					\
+	emitter_gen_fmt(fmt, FMT_SIZE, format, justify, width);		\
+	emitter_printf(emitter, fmt, *(const type *)value);		\
+
+	switch (value_type) {
+	case emitter_type_bool:
+		emitter_gen_fmt(fmt, FMT_SIZE, "s", justify, width);
+		emitter_printf(emitter, fmt, *(const bool *)value ?
+		    "true" : "false");
+		break;
+	case emitter_type_int:
+		EMIT_SIMPLE(int, "d")
+		break;
+	case emitter_type_unsigned:
+		EMIT_SIMPLE(unsigned, "u")
+		break;
+	case emitter_type_ssize:
+		EMIT_SIMPLE(ssize_t, "zd")
+		break;
+	case emitter_type_size:
+		EMIT_SIMPLE(size_t, "zu")
+		break;
+	case emitter_type_string:
+		str_written = malloc_snprintf(buf, BUF_SIZE, "\"%s\"",
+		    *(const char *const *)value);
+		/*
+		 * We control the strings we output; we shouldn't get anything
+		 * anywhere near the fmt size.
+		 */
+		assert(str_written < BUF_SIZE);
+
+		/*
+		 * We don't support justified quoted string primitive values for
+		 * now. Fortunately, we don't want to emit them.
+		 */
+
+		emitter_gen_fmt(fmt, FMT_SIZE, "s", justify, width);
+		emitter_printf(emitter, fmt, buf);
+		break;
+	case emitter_type_uint32:
+		EMIT_SIMPLE(uint32_t, FMTu32)
+		break;
+	case emitter_type_uint64:
+		EMIT_SIMPLE(uint64_t, FMTu64)
+		break;
+	default:
+		unreachable();
+	}
+#undef BUF_SIZE
+#undef FMT_SIZE
+}
+
+
+/* Internal functions.  In json mode, tracks nesting state. */
+static inline void
+emitter_nest_inc(emitter_t *emitter) {
+	emitter->nesting_depth++;
+	emitter->item_at_depth = false;
+}
+
+static inline void
+emitter_nest_dec(emitter_t *emitter) {
+	emitter->nesting_depth--;
+	emitter->item_at_depth = true;
+}
+
+static inline void
+emitter_indent(emitter_t *emitter) {
+	int amount = emitter->nesting_depth;
+	const char *indent_str;
+	if (emitter->output == emitter_output_json) {
+		indent_str = "\t";
+	} else {
+		amount *= 2;
+		indent_str = " ";
+	}
+	for (int i = 0; i < amount; i++) {
+		emitter_printf(emitter, "%s", indent_str);
+	}
+}
+
+static inline void
+emitter_json_key_prefix(emitter_t *emitter) {
+	emitter_printf(emitter, "%s\n", emitter->item_at_depth ? "," : "");
+	emitter_indent(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 {
+		// tabular init
+		emitter_printf(emitter, "");
+	}
+}
+
+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");
+	}
+}
+
+/*
+ * 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) {
+		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,
+		    value_type, value);
+		if (table_note_key != NULL) {
+			emitter_printf(emitter, " (%s: ", table_note_key);
+			emitter_print_value(emitter, emitter_justify_none, -1,
+			    table_note_value_type, table_note_value);
+			emitter_printf(emitter, ")");
+		}
+		emitter_printf(emitter, "\n");
+	}
+	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_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);
+	}
+}
+
+static inline void
+emitter_table_kv(emitter_t *emitter, const char *table_key,
+    emitter_type_t value_type, const void *value) {
+	if (emitter->output == emitter_output_table) {
+		emitter_kv(emitter, NULL, table_key, value_type, value);
+	}
+}
+
+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);
+	}
+}
+
+#endif /* JEMALLOC_INTERNAL_EMITTER_H */