From 7e192f00497c9837856530d2ca5559ec86715502 Mon Sep 17 00:00:00 2001 From: Sebastian Harl Date: Fri, 31 Oct 2014 18:48:34 +0100 Subject: [PATCH] store: Added a generic JSON formatter. It works by consuming single objects of any type (host, service, metric, attribute) at a time and appending their JSON serialization to a string buffer. The current position in the object tree is recorded in an internal state. A helper function is provided on top of the base formatter which allows to handle an full object at a time. --- src/Makefile.am | 1 + src/core/store-private.h | 1 + src/core/store_json.c | 241 +++++++++++++++++++++++++++++++++++++++ src/include/core/store.h | 59 ++++++++++ 4 files changed, 302 insertions(+) create mode 100644 src/core/store_json.c diff --git a/src/Makefile.am b/src/Makefile.am index c8ad524..64b6ec4 100644 --- a/src/Makefile.am +++ b/src/Makefile.am @@ -72,6 +72,7 @@ libsysdb_la_SOURCES = \ core/store.c include/core/store.h \ core/store-private.h \ core/store_expr.c \ + core/store_json.c \ core/store_lookup.c \ core/data.c include/core/data.h \ core/timeseries.c include/core/timeseries.h \ diff --git a/src/core/store-private.h b/src/core/store-private.h index 775057f..953a882 100644 --- a/src/core/store-private.h +++ b/src/core/store-private.h @@ -106,6 +106,7 @@ typedef struct { /* * expressions */ + enum { ATTR_VALUE = -2, /* attr name stored in data.data.string */ FIELD_VALUE = -1, /* field type stored in data.data.integer */ diff --git a/src/core/store_json.c b/src/core/store_json.c new file mode 100644 index 0000000..d9fc37c --- /dev/null +++ b/src/core/store_json.c @@ -0,0 +1,241 @@ +/* + * SysDB - src/core/store_json.c + * Copyright (C) 2013-2014 Sebastian 'tokkee' Harl + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED + * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR + * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDERS OR + * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, + * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, + * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; + * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, + * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR + * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF + * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + */ + +/* + * This module implements JSON support. + */ + +#if HAVE_CONFIG_H +# include "config.h" +#endif /* HAVE_CONFIG_H */ + +#include "sysdb.h" +#include "core/store-private.h" +#include "utils/error.h" + +#include + +#include + +/* + * private data types + */ + +struct sdb_store_json_formatter { + sdb_strbuf_t *buf; + + /* The context describes the state of the formatter through + * the path pointing to the current object */ + int context[8]; + size_t current; +}; + +/* + * private helper functions + */ + +static int +json_emit(sdb_store_json_formatter_t *f, sdb_store_obj_t *obj) +{ + char time_str[64]; + char interval_str[64]; + size_t i; + + assert(f && obj); + + sdb_strbuf_append(f->buf, "{\"name\": \"%s\", ", SDB_OBJ(obj)->name); + if (obj->type == SDB_ATTRIBUTE) { + char tmp[sdb_data_strlen(&ATTR(obj)->value) + 1]; + if (sdb_data_format(&ATTR(obj)->value, tmp, sizeof(tmp), + SDB_DOUBLE_QUOTED) < 0) + snprintf(tmp, sizeof(tmp), ""); + sdb_strbuf_append(f->buf, "\"value\": %s, ", tmp); + } + + /* TODO: make time and interval formats configurable */ + if (! sdb_strftime(time_str, sizeof(time_str), + "%F %T %z", obj->last_update)) + snprintf(time_str, sizeof(time_str), ""); + time_str[sizeof(time_str) - 1] = '\0'; + + if (! sdb_strfinterval(interval_str, sizeof(interval_str), + obj->interval)) + snprintf(interval_str, sizeof(interval_str), ""); + interval_str[sizeof(interval_str) - 1] = '\0'; + + sdb_strbuf_append(f->buf, "\"last_update\": \"%s\", " + "\"update_interval\": \"%s\", \"backends\": [", + time_str, interval_str); + + for (i = 0; i < obj->backends_num; ++i) { + sdb_strbuf_append(f->buf, "\"%s\"", obj->backends[i]); + if (i < obj->backends_num - 1) + sdb_strbuf_append(f->buf, ","); + } + sdb_strbuf_append(f->buf, "]"); + return 0; +} /* json_emit */ + +/* + * public API + */ + +sdb_store_json_formatter_t * +sdb_store_json_formatter(sdb_strbuf_t *buf) +{ + sdb_store_json_formatter_t *f; + + if (! buf) + return NULL; + + f = calloc(1, sizeof(*f)); + if (! f) + return NULL; + + f->buf = buf; + f->context[0] = 0; + f->current = 0; + return f; +} /* sdb_store_json_formatter */ + +int +sdb_store_json_emit(sdb_store_json_formatter_t *f, sdb_store_obj_t *obj) +{ + if ((! f) || (! obj)) + return -1; + + /* first host */ + if (! f->context[0]) { + assert(f->current == 0); + f->context[0] = SDB_HOST; + return json_emit(f, obj); + } + + if (obj->type == f->context[f->current]) { + /* new entry of the same type */ + sdb_strbuf_append(f->buf, "},"); + } + else if ((f->context[f->current] == SDB_HOST) + || (obj->type == SDB_ATTRIBUTE)) { + assert(obj->type != SDB_HOST); + /* all object types may be children of a host; + * attributes may be children of any type */ + sdb_strbuf_append(f->buf, ", \"%ss\": [", + SDB_STORE_TYPE_TO_NAME(obj->type)); + ++f->current; + } + else if (f->current >= 1) { + /* new entry of a previous type or a new type on the same level + * -> rewind to the right state and then handle the new object */ + assert(obj->type != SDB_ATTRIBUTE); + while (f->current > 0) { + if (f->context[f->current] == obj->type) + break; + assert(f->context[f->current] != SDB_HOST); + sdb_strbuf_append(f->buf, "}]"); + --f->current; + } + return sdb_store_json_emit(f, obj); + } + else { + sdb_log(SDB_LOG_ERR, "store: Unexpected object of type %s " + "on level %zu during JSON serialization", + SDB_STORE_TYPE_TO_NAME(obj->type), f->current); + return -1; + } + + json_emit(f, obj); + assert(f->current < SDB_STATIC_ARRAY_LEN(f->context)); + f->context[f->current] = obj->type; + return 0; +} /* sdb_store_json_emit */ + +int +sdb_store_json_emit_full(sdb_store_json_formatter_t *f, sdb_store_obj_t *obj, + sdb_store_matcher_t *filter) +{ + sdb_avltree_t *trees[] = { NULL, NULL, NULL }; + size_t i; + + if (sdb_store_json_emit(f, obj)) + return -1; + + if (obj->type == SDB_HOST) { + trees[0] = HOST(obj)->attributes; + trees[1] = HOST(obj)->metrics; + trees[2] = HOST(obj)->services; + } + else if (obj->type == SDB_SERVICE) + trees[0] = SVC(obj)->attributes; + else if (obj->type == SDB_METRIC) + trees[0] = METRIC(obj)->attributes; + else if (obj->type == SDB_ATTRIBUTE) + return 0; + else + return -1; + + for (i = 0; i < SDB_STATIC_ARRAY_LEN(trees); ++i) { + sdb_avltree_iter_t *iter; + + if (! trees[i]) + continue; + + iter = sdb_avltree_get_iter(trees[i]); + while (sdb_avltree_iter_has_next(iter)) { + sdb_store_obj_t *child; + child = STORE_OBJ(sdb_avltree_iter_get_next(iter)); + + if (filter && (! sdb_store_matcher_matches(filter, child, NULL))) + continue; + + if (sdb_store_json_emit_full(f, child, filter)) { + sdb_avltree_iter_destroy(iter); + return -1; + } + } + sdb_avltree_iter_destroy(iter); + } + return 0; +} /* sdb_store_json_emit_full */ + +int +sdb_store_json_finish(sdb_store_json_formatter_t *f) +{ + if (! f) + return -1; + + while (f->current > 0) { + sdb_strbuf_append(f->buf, "}]"); + --f->current; + } + if (f->context[0]) + sdb_strbuf_append(f->buf, "}"); + return 0; +} /* sdb_store_json_finish */ + +/* vim: set tw=78 sw=4 ts=4 noexpandtab : */ + diff --git a/src/include/core/store.h b/src/include/core/store.h index 2720db4..6dd7d1a 100644 --- a/src/include/core/store.h +++ b/src/include/core/store.h @@ -88,6 +88,13 @@ struct sdb_store_matcher; typedef struct sdb_store_matcher sdb_store_matcher_t; #define SDB_STORE_MATCHER(obj) ((sdb_store_matcher_t *)(obj)) +/* + * A JSON formatter converts a stored object into the JSON format. + * See http://www.ietf.org/rfc/rfc4627.txt + */ +struct sdb_store_json_formatter; +typedef struct sdb_store_json_formatter sdb_store_json_formatter_t; + /* * Queryable fields of a stored object. */ @@ -612,6 +619,58 @@ int sdb_store_host_tojson(sdb_store_obj_t *host, sdb_strbuf_t *buf, sdb_store_matcher_t *filter, int flags); +/* + * sdb_store_json_formatter: + * Create a JSON formatter writing to the specified buffer. + */ +sdb_store_json_formatter_t * +sdb_store_json_formatter(sdb_strbuf_t *buf); + +/* + * sdb_store_json_emit: + * Serialize a single object to JSON adding it to the string buffer associated + * with the formatter object. The serialized object will not include + * attributes or any child objects. Instead, call the function again for each + * of those objects. All attributes have to be emitted before any other + * children types. Use sdb_store_json_emit_full() to emit a full (filtered) + * object. + * + * Note that the output might not be valid JSON before calling + * sdb_store_json_finish(). + * + * Returns: + * - 0 on success + * - a negative value else + */ +int +sdb_store_json_emit(sdb_store_json_formatter_t *f, sdb_store_obj_t *obj); + +/* + * sdb_store_json_emit_full: + * Serialize a single object including it's attributes and all children to + * JSON, adding it to the string buffer associated with the formatter object. + * The filter, if specified, is applied to each attribute and child object. + * Only matching objects will be included in the output. + * + * Note that the output might not be valid JSON before calling + * sdb_store_json_finish(). + * + * Returns: + * - 0 on success + * - a negative value else + */ +int +sdb_store_json_emit_full(sdb_store_json_formatter_t *f, sdb_store_obj_t *obj, + sdb_store_matcher_t *filter); + +/* + * sdb_store_json_finish: + * Finish the JSON output. This function has to be called once after emiting + * all objects. + */ +int +sdb_store_json_finish(sdb_store_json_formatter_t *f); + #ifdef __cplusplus } /* extern "C" */ #endif -- 2.30.2