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/*
* Copyright 2018 Google LLC
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* https://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef NANO_EXPORTER_SCRAPE_H_
#define NANO_EXPORTER_SCRAPE_H_ 1
#include <stdbool.h>
#include <stddef.h>
/** Opaque type to represent the scrape server. */
typedef struct scrape_server scrape_server;
/** Opaque type to represent an ongoing scrape request. */
typedef struct scrape_req scrape_req;
/** Function type for a scrape server callback. */
typedef void scrape_handler(scrape_req *req, void *ctx);
/** Sets up a scrape server listening at the given port. */
scrape_server *scrape_listen(const char *port);
/** Enters a loop serving scrape requests using the provided handler. */
void scrape_serve(scrape_server *server, scrape_handler *handler, void *handler_ctx);
/** Closes the scrape server sockets and frees any resources. */
void scrape_close(scrape_server *server);
/** Container for label keys and values. */
struct label {
char *key;
char *value;
};
#define LABEL_END ((struct label){ .key = 0, .value = 0 })
#define LABEL_LIST(...) ((struct label[]){ __VA_ARGS__, LABEL_END })
/**
* Writes a metric value as a response to a scrape.
*
* The \p labels parameter can be `NULL` if no extra labels need to be
* attached. If not null, it should point at the first element of an
* array of `struct label` objects, terminated by a sentinel value
* with a null pointer as the key.
*
* Returns `false` if setting up the server failed, otherwise does not return.
*/
void scrape_write(scrape_req *req, const char *metric, const struct label *labels, double value);
/**
* Writes raw data to the scrape response.
*
* It's the callers responsibility to make sure it writes syntactically valid metric data.
*/
void scrape_write_raw(scrape_req *req, const void *buf, size_t len);
#endif // NANO_EXPORTER_SCRAPE_H_
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