#ifndef __CURL_MULTI_H #define __CURL_MULTI_H /***************************************************************************** * _ _ ____ _ * Project ___| | | | _ \| | * / __| | | | |_) | | * | (__| |_| | _ <| |___ * \___|\___/|_| \_\_____| * * Copyright (C) 2001, Daniel Stenberg, , et al. * * In order to be useful for every potential user, curl and libcurl are * dual-licensed under the MPL and the MIT/X-derivate licenses. * * You may opt to use, copy, modify, merge, publish, distribute and/or sell * copies of the Software, and permit persons to whom the Software is * furnished to do so, under the terms of the MPL or the MIT/X-derivate * licenses. You may pick one of these licenses. * * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY * KIND, either express or implied. * * $Id$ *****************************************************************************/ /* This is meant to be the "external" header file. Don't give away any internals here! This document presents a mixture of ideas from at least: - Daniel Stenberg - Steve Dekorte - Sterling Hughes - Ben Greear ------------------------------------------- GOALS o Enable a "pull" interface. The application that uses libcurl decides where and when to ask libcurl to get/send data. o Enable multiple simultaneous transfers without using threads or making it very complicated for the application. o Enable the application to select() on its own file descriptors and curl's file descriptors simultaneous easily. Example source using this interface: http://curl.haxx.se/dev/multi-app.c */ #ifdef HAVE_SYS_SOCKET_H #include #endif #include typedef void CURLM; typedef enum { CURLM_OK, CURLM_BAD_HANDLE, /* the passed-in handle is not a valid CURLM handle */ CURLM_BAD_EASY_HANDLE, /* an easy handle was not good/valid */ CURLM_OUT_OF_MEMORY, /* if you ever get this, you're in deep sh*t */ CURLM_LAST } CURLMcode; struct CURLMsg { CURL *easy_handle; void *whatever; }; typedef struct CURLMsg CURLMsg; typedef void * CURLMinfo; /* * Desc: inititalize multi-style curl usage * Name: curl_multi_init() * Returns: a new CURLM handle to use in all 'curl_multi' functions. */ CURLM *curl_multi_init(void); /* * Desc: add a standard curl handle to the multi stack * Name: curl_multi_add_handle() * Returns: CURLMcode type, general error code. */ CURLMcode curl_multi_add_handle(CURLM *multi_handle, CURL *curl_handle); /* * Desc: removes a curl handle from the multi stack again * Name: curl_multi_remove_handle() * Returns: CURLMcode type, general error code. */ CURLMcode curl_multi_remove_handle(CURLM *multi_handle, CURL *curl_handle); /* * Desc: Ask curl for its fd_set sets. The app can use these to select() or * poll() on. We want curl_multi_perform() called as soon as one of * them are ready. * Name: curl_multi_fdset() * Returns: CURLMcode type, general error code. */ CURLMcode curl_multi_fdset(CURLM *multi_handle, fd_set *read_fd_set, fd_set *write_fd_set, fd_set *exc_fd_set, int *max_fd); /* * Desc: When the app thinks there's data available for curl it calls this * function to read/write whatever there is right now. This returns * as soon as the reads and writes are done. This function does not * require that there actually is data available for reading or that * data can be written, it can be called just in case. It returns * the number of handles that still transfer data in the second * argument's integer-pointer. * Name: curl_multi_fdset() * Returns: CURLMcode type, general error code. *NOTE* that this only returns * errors etc regardin the whole multi stack. There might still have * occurred problems on invidual transfers even when this returns OK. */ CURLMcode curl_multi_perform(CURLM *multi_handle, int *running_handles); /* * Desc: Cleans up and removes a whole multi stack. * Name: curl_multi_cleanup() * Returns: CURLMcode type, general error code. */ CURLMcode curl_multi_cleanup(CURLM *multi_handle); /* ---------------------------------------------------------------------- */ /* * I suggest an fopen style system to get information from the multi layer. * I've named these functions "curl_multi_info*" something to make it apparent * that they belong together. * * I expect that the curl_multi_info_open will be used fairly often after * calls to curl_multi_perform(), but there's nothing in this design that * forces the application to invoke it at that particular time. In fact, many * applications will do good without using it at all. */ /* * Desc: Ask the multi handle if there's any messages/informationals from * the individual transfers. We pass a pointer to a 'CURLMinfo' that * can be used as input in a subsequent call to curl_multi_info_read. * * Messages include informationals such as error code from the * transfer or just the fact that a transfer is completed. More * details on these should be written down as well. * * Name: curl_multi_info_open() * Returns: The number of transfers that have information stored that can be * read. If zero is returned, there's no need to call * curl_multi_info_close() on the returned handle, but there's no * harm in doing so. */ int curl_multi_info_open(CURLM *multi_handle, CURLMinfo *info_handle); /* * Desc: Returns a pointer to a filled-in struct with information. * * Repeated calls to this function will return a new struct each * time, until a special "end of msgs" struct is returned as a signal * that there is no more to get at this point. * * curl_multi_info_close() should be called when the last info has * been read. In fact, it must be called if curl_multi_info_open() * was called. * * The data the returned pointer points to will not survive calling * curl_multi_cleanup(). * * The 'CURLMsg' struct is meant to be very simple and only contain * very basic informations. If more involved information is wanted, * we will provide the particular "transfer handle" in that struct * and that should/could/would be used in subsequent * curl_easy_getinfo() calls (or similar). The point being that we * must never expose complex structs to applications, as then we'll * undoubtably get backwards compatibility problems in the future. * * Name: curl_multi_info_read() * * Returns: A pointer to a struct, or NULL if it failed or ran out of structs. * Note that if you continue reading until you get a NULL, you did * read at least one too many times! */ CURLMsg *curl_multi_info_read(CURLMinfo *info_handle); /* * Desc: Terminates an info reading "session". * * Name: curl_multi_info_close() * * Returns: When we've read all the info we want from the info_handle, we * signal this to the multi system by calling this function. * After this call, the info_handle can no longer be used. * */ void curl_multi_info_close(CURLMinfo *info_handle); #endif