tdlight/td/telegram/td_json_client.h

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//
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// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2021
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//
#pragma once
/**
* \file
* C interface for interaction with TDLib via JSON-serialized objects.
* Can be used to easily integrate TDLib with any programming language which supports calling C functions
* and is able to work with JSON.
*
* The JSON serialization of TDLib API objects is straightforward: all API objects are represented as JSON objects with
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* the same keys as the API object field names. The object type name is stored in the special field "@type" which is
* optional in places where type is uniquely determined by the context.
* Fields of Bool type are stored as Boolean, fields of int32, int53, and double types are stored as Number, fields of
* int64 and string types are stored as String, fields of bytes type are base64 encoded and then stored as String,
* fields of array type are stored as Array.
* The main TDLib interface is asynchronous. To match requests with a corresponding response a field "@extra" can
* be added to the request object. The corresponding response will have an "@extra" field with exactly the same value.
*
* A TDLib client instance can be created through td_json_client_create.
* Requests then can be sent using td_json_client_send from any thread.
* New updates and request responses can be received through td_json_client_receive from any thread. This function
* must not be called simultaneously from two different threads. Also note that all updates and request responses
* must be applied in the order they were received to ensure consistency.
* Given this information, it's advisable to call this function from a dedicated thread.
* Some service TDLib requests can be executed synchronously from any thread by using td_json_client_execute.
* The TDLib client instance can be destroyed via td_json_client_destroy.
*
* General pattern of usage:
* \code
* void *client = td_json_client_create();
* // somehow share the client with other threads, which will be able to send requests via td_json_client_send
*
* const double WAIT_TIMEOUT = 10.0; // seconds
* int is_closed = 0; // should be set to 1, when updateAuthorizationState with authorizationStateClosed is received
* while (!is_closed) {
* const char *result = td_json_client_receive(client, WAIT_TIMEOUT);
* if (result) {
* // parse the result as JSON object and process it as an incoming update or an answer to a previously sent request
* }
* }
* td_json_client_destroy(client);
* \endcode
*/
#include "td/telegram/tdjson_export.h"
#ifdef __cplusplus
extern "C" {
#endif
/**
* Creates a new instance of TDLib.
* \return Pointer to the created instance of TDLib.
*/
TDJSON_EXPORT void *td_json_client_create();
/**
* Sends request to the TDLib client. May be called from any thread.
* \param[in] client The client.
* \param[in] request JSON-serialized null-terminated request to TDLib.
*/
TDJSON_EXPORT void td_json_client_send(void *client, const char *request);
/**
* Receives incoming updates and request responses from the TDLib client. May be called from any thread, but
* must not be called simultaneously from two different threads.
* Returned pointer will be deallocated by TDLib during next call to td_json_client_receive or td_json_client_execute
* in the same thread, so it can't be used after that.
* \param[in] client The client.
* \param[in] timeout The maximum number of seconds allowed for this function to wait for new data.
* \return JSON-serialized null-terminated incoming update or request response. May be NULL if the timeout expires.
*/
TDJSON_EXPORT const char *td_json_client_receive(void *client, double timeout);
/**
* Synchronously executes TDLib request. May be called from any thread.
* Only a few requests can be executed synchronously.
* Returned pointer will be deallocated by TDLib during next call to td_json_client_receive or td_json_client_execute
* in the same thread, so it can't be used after that.
* \param[in] client The client. Currently ignored for all requests, so NULL can be passed.
* \param[in] request JSON-serialized null-terminated request to TDLib.
* \return JSON-serialized null-terminated request response.
*/
TDJSON_EXPORT const char *td_json_client_execute(void *client, const char *request);
/**
* Destroys the TDLib client instance. After this is called the client instance must not be used anymore.
* \param[in] client The client.
*/
TDJSON_EXPORT void td_json_client_destroy(void *client);
/*
* New TDLib JSON interface.
*
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* The main TDLib interface is asynchronous. To match requests with a corresponding response, the field "@extra" can
* be added to the request object. The corresponding response will have an "@extra" field with exactly the same value.
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* Each returned object will have an "@client_id" field, containing the identifier of the client for which
* a response or an update was received.
*
* A TDLib client instance can be created through td_create_client_id.
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* Requests can be sent using td_send and the received client identifier.
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* New updates and responses to requests can be received through td_receive from any thread after the first request
* has been sent to the client instance. This function must not be called simultaneously from two different threads.
* Also note that all updates and responses to requests must be applied in the order they were received for consistency.
* Some TDLib requests can be executed synchronously from any thread using td_execute.
* TDLib client instances are destroyed automatically after they are closed.
*
* General pattern of usage:
* \code
* int client_id = td_create_client_id();
* // share the client_id with other threads, which will be able to send requests via td_send
*
* const double WAIT_TIMEOUT = 10.0; // seconds
* while (true) {
* const char *result = td_receive(WAIT_TIMEOUT);
* if (result) {
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* // parse the result as a JSON object and process it as an incoming update or the answer to a previously sent request
* }
* }
* \endcode
*/
/**
* Returns an opaque identifier of a new TDLib instance.
* The TDLib instance will not send updates until the first request is sent to it.
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* \return Opaque identifier of a new TDLib instance.
*/
TDJSON_EXPORT int td_create_client_id();
/**
* Sends request to the TDLib client. May be called from any thread.
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* \param[in] client_id TDLib client identifier.
* \param[in] request JSON-serialized null-terminated request to TDLib.
*/
TDJSON_EXPORT void td_send(int client_id, const char *request);
/**
* Receives incoming updates and request responses. Must not be called simultaneously from two different threads.
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* The returned pointer can be used until the next call to td_receive or td_execute, after which it will be deallocated by TDLib.
* \param[in] timeout The maximum number of seconds allowed for this function to wait for new data.
* \return JSON-serialized null-terminated incoming update or request response. May be NULL if the timeout expires.
*/
TDJSON_EXPORT const char *td_receive(double timeout);
/**
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* Synchronously executes a TDLib request.
* A request can be executed synchronously, only if it is documented with "Can be called synchronously".
* The returned pointer can be used until the next call to td_receive or td_execute, after which it will be deallocated by TDLib.
* \param[in] request JSON-serialized null-terminated request to TDLib.
* \return JSON-serialized null-terminated request response.
*/
TDJSON_EXPORT const char *td_execute(const char *request);
/**
* A type of callback function that will be called when a message is added to the internal TDLib log.
*
* \param verbosity_level Log verbosity level with which the message was added.
* \param message Null-terminated string with the logged message.
*/
typedef void (*td_log_message_callback_ptr)(int verbosity_level, const char *message);
/**
* Sets the callback that will be called when a message is added to the internal TDLib log.
* None of the TDLib methods can be called from the callback.
* If message verbosity level is 0, then TDLib will crash as soon as callback returns.
* By default the callback is not set.
*
* \param[in] max_verbosity_level Maximum verbosity level of messages for which the callback will be called.
* \param[in] callback Callback that will be called when a message is added to the internal TDLib log.
* Pass nullptr to remove the callback.
*/
TDJSON_EXPORT void td_set_log_message_callback(int max_verbosity_level, td_log_message_callback_ptr callback);
#ifdef __cplusplus
} // extern "C"
#endif