Edit
kc3-lang/libevent/evbuffer-internal.h
Nick Mathewson
- evbuffer-internal.h
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/* * Copyright (c) 2000-2007 Niels Provos <provos@citi.umich.edu> * Copyright (c) 2007-2009 Niels Provos and Nick Mathewson * * 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. * 3. The name of the author may not be used to endorse or promote products * derived from this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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. */ #ifndef _EVBUFFER_INTERNAL_H_ #define _EVBUFFER_INTERNAL_H_ #ifdef __cplusplus extern "C" { #endif #include "event-config.h" #include "event2/util.h" #include "util-internal.h" #include "defer-internal.h" #ifdef WIN32 #include <winsock2.h> #endif #include <sys/queue.h> /* minimum allocation for a chain. */ #define MIN_BUFFER_SIZE 256 /** A single evbuffer callback for an evbuffer. This function will be invoked * when bytes are added to or removed from the evbuffer. */ struct evbuffer_cb_entry { /** Structures to implement a doubly-linked queue of callbacks */ TAILQ_ENTRY(evbuffer_cb_entry) next; /** The callback function to invoke when this callback is called. If EVBUFFER_CB_OBSOLETE is set in flags, the cb_obsolete field is valid; otherwise, cb_func is valid. */ union { evbuffer_cb_func cb_func; evbuffer_cb cb_obsolete; } cb; /** Argument to pass to cb. */ void *cbarg; /** Currently set flags on this callback. */ ev_uint32_t flags; #if 0 /** Size of the evbuffer before this callback was suspended, or 0 if this callback is not suspended. */ size_t size_before_suspend; #endif }; struct evbuffer_chain; struct evbuffer { /** The first chain in this buffer's linked list of chains. */ struct evbuffer_chain *first; /** The last chain in this buffer's linked list of chains. */ struct evbuffer_chain *last; /** The next-to-last chain in this buffer's linked list of chains. * NULL if the buffer has 0 or 1 chains. Used in case there's an * ongoing read that needs to be split across multiple chains: we want * to add a new chain as a read target, but we don't want to lose our * pointer to the next-to-last chain if the read turns out to be * incomplete. */ /* FIXME: This should probably be called last_with_space and * repurposed accordingly. */ struct evbuffer_chain *previous_to_last; /** Total amount of bytes stored in all chains.*/ size_t total_len; /** Number of bytes we have added to the buffer since we last tried to * invoke callbacks. */ size_t n_add_for_cb; /** Number of bytes we have removed from the buffer since we last * tried to invoke callbacks. */ size_t n_del_for_cb; #ifndef _EVENT_DISABLE_THREAD_SUPPORT /** A lock used to mediate access to this buffer. */ void *lock; #endif /** True iff we should free the lock field when we free this * evbuffer. */ unsigned own_lock : 1; /** True iff we should not allow changes to the front of the buffer * (drains or prepends). */ unsigned freeze_start : 1; /** True iff we should not allow changes to the end of the buffer * (appends) */ unsigned freeze_end : 1; /** True iff this evbuffer's callbacks are not invoked immediately * upon a change in the buffer, but instead are deferred to be invoked * from the event_base's loop. Useful for preventing enormous stack * overflows when we have mutually recursive callbacks, and for * serializing callbacks in a single thread. */ unsigned deferred_cbs : 1; #ifdef WIN32 /** True iff this buffer is set up for overlapped IO. */ unsigned is_overlapped : 1; #endif /** Used to implement deferred callbacks. */ struct deferred_cb_queue *cb_queue; /** For debugging: how many times have we acquired the lock for this * evbuffer? */ int lock_count; /** A reference count on this evbuffer. When the reference count * reaches 0, the buffer is destroyed. Manipulated with * evbuffer_incref and evbuffer_decref_and_unlock and * evbuffer_free. */ int refcnt; /** A deferred_cb handle to make all of this buffer's callbacks * invoked from the event loop. */ struct deferred_cb deferred; /** A doubly-linked-list of callback functions */ TAILQ_HEAD(evbuffer_cb_queue, evbuffer_cb_entry) callbacks; }; /** A single item in an evbuffer. */ struct evbuffer_chain { /** points to next buffer in the chain */ struct evbuffer_chain *next; /** total allocation available in the buffer field. */ size_t buffer_len; /** unused space at the beginning of buffer or an offset into a * file for sendfile buffers. */ off_t misalign; /** Offset into buffer + misalign at which to start writing. * In other words, the total number of bytes actually stored * in buffer. */ size_t off; /** Set if special handling is required for this chain */ unsigned flags; #define EVBUFFER_MMAP 0x0001 /**< memory in buffer is mmaped */ #define EVBUFFER_SENDFILE 0x0002 /**< a chain used for sendfile */ #define EVBUFFER_REFERENCE 0x0004 /**< a chain with a mem reference */ #define EVBUFFER_IMMUTABLE 0x0008 /**< read-only chain */ /** a chain that mustn't be reallocated or freed, or have its contents * memmoved, until the chain is un-pinned. */ #define EVBUFFER_MEM_PINNED_R 0x0010 #define EVBUFFER_MEM_PINNED_W 0x0020 #define EVBUFFER_MEM_PINNED_ANY (EVBUFFER_MEM_PINNED_R|EVBUFFER_MEM_PINNED_W) /** a chain that should be freed, but can't be freed until it is * un-pinned. */ #define EVBUFFER_DANGLING 0x0040 /** Usually points to the read-write memory belonging to this * buffer allocated as part of the evbuffer_chain allocation. * For mmap, this can be a read-only buffer and * EVBUFFER_IMMUTABLE will be set in flags. For sendfile, it * may point to NULL. */ unsigned char *buffer; }; /* this is currently used by both mmap and sendfile */ /* TODO(niels): something strange needs to happen for Windows here, I am not * sure what that is, but it needs to get looked into. */ struct evbuffer_chain_fd { int fd; /**< the fd associated with this chain */ }; /** callback for a reference buffer; lets us know what to do with it when * we're done with it. */ struct evbuffer_chain_reference { evbuffer_ref_cleanup_cb cleanupfn; void *extra; }; #define EVBUFFER_CHAIN_SIZE sizeof(struct evbuffer_chain) /** Return a pointer to extra data allocated along with an evbuffer. */ #define EVBUFFER_CHAIN_EXTRA(t, c) (t *)((struct evbuffer_chain *)(c) + 1) /** Assert that somebody (hopefully us) is holding the lock on an evbuffer */ #define ASSERT_EVBUFFER_LOCKED(buffer) \ do { \ assert((buffer)->lock_count > 0); \ } while (0) /** Assert that nobody is holding the lock on an evbuffer */ #define ASSERT_EVBUFFER_UNLOCKED(buffer) \ do { \ assert((buffer)->lock_count == 0); \ } while (0) #define _EVBUFFER_INCREMENT_LOCK_COUNT(buffer) \ do { \ ((struct evbuffer*)(buffer))->lock_count++; \ } while (0) #define _EVBUFFER_DECREMENT_LOCK_COUNT(buffer) \ do { \ ASSERT_EVBUFFER_LOCKED(buffer); \ ((struct evbuffer*)(buffer))->lock_count--; \ } while (0) #define EVBUFFER_LOCK(buffer, mode) \ do { \ EVLOCK_LOCK((buffer)->lock, (mode)); \ _EVBUFFER_INCREMENT_LOCK_COUNT(buffer); \ } while(0) #define EVBUFFER_UNLOCK(buffer, mode) \ do { \ _EVBUFFER_DECREMENT_LOCK_COUNT(buffer); \ EVLOCK_UNLOCK((buffer)->lock, (mode)); \ } while(0) #define EVBUFFER_LOCK2(buffer1, buffer2) \ do { \ EVLOCK_LOCK2((buffer1)->lock, (buffer2)->lock, \ EVTHREAD_WRITE, EVTHREAD_WRITE); \ _EVBUFFER_INCREMENT_LOCK_COUNT(buffer1); \ _EVBUFFER_INCREMENT_LOCK_COUNT(buffer2); \ } while(0) #define EVBUFFER_UNLOCK2(buffer1, buffer2) \ do { \ _EVBUFFER_DECREMENT_LOCK_COUNT(buffer1); \ _EVBUFFER_DECREMENT_LOCK_COUNT(buffer2); \ EVLOCK_UNLOCK2((buffer1)->lock, (buffer2)->lock, \ EVTHREAD_WRITE, EVTHREAD_WRITE); \ } while(0) /** Increase the reference count of buf by one. */ void _evbuffer_incref(struct evbuffer *buf); /** Pin a single buffer chain using a given flag. A pinned chunk may not be * moved or freed until it is unpinned. */ void _evbuffer_chain_pin(struct evbuffer_chain *chain, unsigned flag); /** Unpin a single buffer chain using a given flag. */ void _evbuffer_chain_unpin(struct evbuffer_chain *chain, unsigned flag); /** As evbuffer_free, but requires that we hold a lock on the buffer, and * releases the lock before freeing it and the buffer. */ void _evbuffer_decref_and_unlock(struct evbuffer *buffer); /** As evbuffer_expand, but does not guarantee that the newly allocated memory * is contiguous. Instead, it may be split across two chunks. */ int _evbuffer_expand_fast(struct evbuffer *, size_t); /** Helper: prepares for a readv/WSARecv call by expanding the buffer to * hold enough memory to read 'howmuch' bytes in possibly noncontiguous memory. * Sets up the one or two iovecs in 'vecs' to point to the free memory and its * extent, and *chainp to point to the first chain that we'll try to read into. * Returns the number of vecs used. */ int _evbuffer_read_setup_vecs(struct evbuffer *buf, ev_ssize_t howmuch, struct evbuffer_iovec *vecs, struct evbuffer_chain **chainp, int exact); /* Helper macro: copies an evbuffer_iovec in ei to a win32 WSABUF in i. */ #define WSABUF_FROM_EVBUFFER_IOV(i,ei) do { \ (i)->buf = (ei)->iov_base; \ (i)->len = (ei)->iov_len; \ } while(0) #ifdef __cplusplus } #endif #endif /* _EVBUFFER_INTERNAL_H_ */