/* Copyright 2015 greenbytes GmbH (https://www.greenbytes.de) * * 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 * * http://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 h2_bucket_beam_h #define h2_bucket_beam_h struct apr_thread_mutex_t; struct apr_thread_cond_t; /******************************************************************************* * apr_bucket list without bells and whistles ******************************************************************************/ /** * h2_blist can hold a list of buckets just like apr_bucket_brigade, but * does not to any allocations or related features. */ typedef struct { APR_RING_HEAD(h2_bucket_list, apr_bucket) list; } h2_blist; #define H2_BLIST_INIT(b) APR_RING_INIT(&(b)->list, apr_bucket, link); #define H2_BLIST_SENTINEL(b) APR_RING_SENTINEL(&(b)->list, apr_bucket, link) #define H2_BLIST_EMPTY(b) APR_RING_EMPTY(&(b)->list, apr_bucket, link) #define H2_BLIST_FIRST(b) APR_RING_FIRST(&(b)->list) #define H2_BLIST_LAST(b) APR_RING_LAST(&(b)->list) #define H2_BLIST_INSERT_HEAD(b, e) do { \ apr_bucket *ap__b = (e); \ APR_RING_INSERT_HEAD(&(b)->list, ap__b, apr_bucket, link); \ } while (0) #define H2_BLIST_INSERT_TAIL(b, e) do { \ apr_bucket *ap__b = (e); \ APR_RING_INSERT_TAIL(&(b)->list, ap__b, apr_bucket, link); \ } while (0) #define H2_BLIST_CONCAT(a, b) do { \ APR_RING_CONCAT(&(a)->list, &(b)->list, apr_bucket, link); \ } while (0) #define H2_BLIST_PREPEND(a, b) do { \ APR_RING_PREPEND(&(a)->list, &(b)->list, apr_bucket, link); \ } while (0) /** * Print the buckets in the list into the buffer (type and lengths). * @param buffer the buffer to print into * @param bmax max number of characters to place in buffer, incl. trailing 0 * @param tag tag string for this bucket list * @param sep separator to use * @param bl the bucket list to print * @return number of characters printed */ apr_size_t h2_util_bl_print(char *buffer, apr_size_t bmax, const char *tag, const char *sep, h2_blist *bl); /******************************************************************************* * h2_bucket_beam ******************************************************************************/ /** * A h2_bucket_beam solves the task of transferring buckets, esp. their data, * across threads with zero buffer copies. * * When a thread, let's call it the red thread, wants to send buckets to * another, the green thread, it creates a h2_bucket_beam and adds buckets * via the h2_beam_send(). It gives the beam to the green thread which then * can receive buckets into its own brigade via h2_beam_receive(). * * Sending and receiving can happen concurrently, if a thread mutex is set * for the beam, see h2_beam_mutex_set. * * The beam can limit the amount of data it accepts via the buffer_size. This * can also be adjusted during its lifetime. When the beam not only gets a * mutex but als a condition variable (in h2_beam_mutex_set()), sends and * receives can be done blocking. A timeout can be set for such blocks. * * Care needs to be taken when terminating the beam. The beam registers at * the pool it was created with and will cleanup after itself. However, if * received buckets do still exist, already freed memory might be accessed. * The beam does a AP_DEBUG_ASSERT on this condition. * * The proper way of shutting down a beam is to first make sure there are no * more green buckets out there, then cleanup the beam to purge eventually * still existing red buckets and then, possibly, terminate the beam itself * (or the pool it was created with). * * The following restrictions apply to bucket transport: * - only EOS and FLUSH meta buckets are copied through. All other meta buckets * are kept in the beams hold. * - all kind of data buckets are transported through: * - transient buckets are converted to heap ones on send * - heap and pool buckets require no extra handling * - buckets with indeterminate length are read on send * - file buckets will transfer the file itself into a new bucket, if allowed * - all other buckets are read on send to make sure data is present * * This assures that when the red thread sends its red buckets, the data * is made accessible while still on the red side. The red bucket then enters * the beams hold storage. * When the green thread calls receive, red buckets in the hold are wrapped * into special beam buckets. Beam buckets on read present the data directly * from the internal red one, but otherwise live on the green side. When a * beam bucket gets destroyed, it notifies its beam that the corresponding * red bucket from the hold may be destroyed. * Since the destruction of green buckets happens in the green thread, any * corresponding red bucket can not immediately be destroyed, as that would * result in race conditions. * Instead, the beam transfers such red buckets from the hold to the purge * storage. Next time there is a call from the red side, the buckets in * purge will be deleted. * * There are callbacks that can be registered with a beam: * - a "consumed" callback that gets called on the red side with the * amount of data that has been received by the green side. The amount * is a delta from the last callback invocation. The red side can trigger * these callbacks by calling h2_beam_send() with a NULL brigade. * - a "can_beam_file" callback that can prohibit the transfer of file handles * through the beam. This will cause file buckets to be read on send and * its data buffer will then be transports just like a heap bucket would. * When no callback is registered, no restrictions apply and all files are * passed through. * File handles transferred to the green side will stay there until the * receiving brigade's pool is destroyed/cleared. If the pool lives very * long or if many different files are beamed, the process might run out * of available file handles. * * The name "beam" of course is inspired by good old transporter * technology where humans are kept inside the transporter's memory * buffers until the transmission is complete. Star gates use a similar trick. */ typedef void h2_beam_mutex_leave(void *ctx, struct apr_thread_mutex_t *lock); typedef struct { apr_thread_mutex_t *mutex; h2_beam_mutex_leave *leave; void *leave_ctx; } h2_beam_lock; typedef struct h2_bucket_beam h2_bucket_beam; typedef apr_status_t h2_beam_mutex_enter(void *ctx, h2_beam_lock *pbl); typedef void h2_beam_io_callback(void *ctx, h2_bucket_beam *beam, apr_off_t bytes); typedef struct h2_beam_proxy h2_beam_proxy; typedef struct { APR_RING_HEAD(h2_beam_proxy_list, h2_beam_proxy) list; } h2_bproxy_list; typedef int h2_beam_can_beam_callback(void *ctx, h2_bucket_beam *beam, apr_file_t *file); struct h2_bucket_beam { int id; const char *tag; h2_blist red; h2_blist hold; h2_blist purge; apr_bucket_brigade *green; h2_bproxy_list proxies; apr_pool_t *red_pool; apr_size_t max_buf_size; apr_interval_time_t timeout; apr_off_t sent_bytes; /* amount of bytes send */ apr_off_t received_bytes; /* amount of bytes received */ apr_size_t buckets_sent; /* # of beam buckets sent */ apr_size_t files_beamed; /* how many file handles have been set aside */ apr_file_t *last_beamed; /* last file beamed */ unsigned int aborted : 1; unsigned int closed : 1; unsigned int close_sent : 1; void *m_ctx; h2_beam_mutex_enter *m_enter; struct apr_thread_cond_t *m_cond; apr_off_t reported_consumed_bytes; /* amount of bytes reported as consumed */ h2_beam_io_callback *consumed_fn; void *consumed_ctx; apr_off_t reported_produced_bytes; /* amount of bytes reported as produced */ h2_beam_io_callback *produced_fn; void *produced_ctx; h2_beam_can_beam_callback *can_beam_fn; void *can_beam_ctx; }; /** * Creates a new bucket beam for transfer of buckets across threads. * * The pool the beam is created with will be protected by the given * mutex and will be used in multiple threads. It needs a pool allocator * that is only used inside that same mutex. * * @param pbeam will hold the created beam on return * @param red_pool pool usable on red side, beam lifeline * @param buffer_size maximum memory footprint of buckets buffered in beam, or * 0 for no limitation * * Call from the red side only. */ apr_status_t h2_beam_create(h2_bucket_beam **pbeam, apr_pool_t *red_pool, int id, const char *tag, apr_size_t buffer_size); /** * Destroys the beam immediately without cleanup. * * Call from the red side only. */ apr_status_t h2_beam_destroy(h2_bucket_beam *beam); /** * Send buckets from the given brigade through the beam. Will hold buckets * internally as long as they have not been processed by the receiving side. * All accepted buckets are removed from the given brigade. Will return with * APR_EAGAIN on non-blocking sends when not all buckets could be accepted. * * Call from the red side only. */ apr_status_t h2_beam_send(h2_bucket_beam *beam, apr_bucket_brigade *red_buckets, apr_read_type_e block); /** * Receive buckets from the beam into the given brigade. Will return APR_EOF * when reading past an EOS bucket. Reads can be blocking until data is * available or the beam has been closed. Non-blocking calls return APR_EAGAIN * if no data is available. * * Call from the green side only. */ apr_status_t h2_beam_receive(h2_bucket_beam *beam, apr_bucket_brigade *green_buckets, apr_read_type_e block, apr_off_t readbytes); /** * Determine if beam is closed. May still contain buffered data. * * Call from red or green side. */ int h2_beam_closed(h2_bucket_beam *beam); /** * Determine if beam is empty. * * Call from red or green side. */ int h2_beam_empty(h2_bucket_beam *beam); /** * Abort the beam. Will cleanup any buffered buckets and answer all send * and receives with APR_ECONNABORTED. * * Call from the red side only. */ void h2_beam_abort(h2_bucket_beam *beam); /** * Close the beam. Sending an EOS bucket serves the same purpose. * * Call from the red side only. */ apr_status_t h2_beam_close(h2_bucket_beam *beam); /** * Return APR_SUCCESS when all buckets in transit have been handled. * When called with APR_BLOCK_READ and a mutex set, will wait until the green * side has consumed all data. Otherwise APR_EAGAIN is returned. * With clear_buffers set, any queued data is discarded. * If a timeout is set on the beam, waiting might also time out and * return APR_ETIMEUP. * * Call from the red side only. */ apr_status_t h2_beam_shutdown(h2_bucket_beam *beam, apr_read_type_e block, int clear_buffers); void h2_beam_mutex_set(h2_bucket_beam *beam, h2_beam_mutex_enter m_enter, struct apr_thread_cond_t *cond, void *m_ctx); /** * Set/get the timeout for blocking read/write operations. Only works * if a mutex has been set for the beam. */ void h2_beam_timeout_set(h2_bucket_beam *beam, apr_interval_time_t timeout); apr_interval_time_t h2_beam_timeout_get(h2_bucket_beam *beam); /** * Set/get the maximum buffer size for beam data (memory footprint). */ void h2_beam_buffer_size_set(h2_bucket_beam *beam, apr_size_t buffer_size); apr_size_t h2_beam_buffer_size_get(h2_bucket_beam *beam); /** * Register a callback to be invoked on the red side with the * amount of bytes that have been consumed by the red side, since the * last callback invocation or reset. * @param beam the beam to set the callback on * @param cb the callback or NULL * @param ctx the context to use in callback invocation * * Call from the red side, callbacks invoked on red side. */ void h2_beam_on_consumed(h2_bucket_beam *beam, h2_beam_io_callback *cb, void *ctx); /** * Register a callback to be invoked on the red side with the * amount of bytes that have been consumed by the red side, since the * last callback invocation or reset. * @param beam the beam to set the callback on * @param cb the callback or NULL * @param ctx the context to use in callback invocation * * Call from the red side, callbacks invoked on red side. */ void h2_beam_on_produced(h2_bucket_beam *beam, h2_beam_io_callback *cb, void *ctx); void h2_beam_on_file_beam(h2_bucket_beam *beam, h2_beam_can_beam_callback *cb, void *ctx); /** * Get the amount of bytes currently buffered in the beam (unread). */ apr_off_t h2_beam_get_buffered(h2_bucket_beam *beam); /** * Get the memory used by the buffered buckets, approximately. */ apr_off_t h2_beam_get_mem_used(h2_bucket_beam *beam); /** * Return != 0 iff (some) data from the beam has been received. */ int h2_beam_was_received(h2_bucket_beam *beam); apr_size_t h2_beam_get_files_beamed(h2_bucket_beam *beam); #endif /* h2_bucket_beam_h */