lws-dsh.h

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/*
 * libwebsockets - small server side websockets and web server implementation
 *
 * Copyright (C) 2010 - 2019 Andy Green <andy@warmcat.com>
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
 * deal in the Software without restriction, including without limitation the
 * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
 * sell copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 * IN THE SOFTWARE.
 */
 
/*
 * lws_dsh (Disordered Shared Heap) is an opaque abstraction supporting a single
 * linear buffer (overallocated at end of the lws_dsh_t) which may contain
 * multiple kinds of packets that are retired out of order, and tracked by kind.
 *
 * Each kind of packet has an lws_dll2 list of its kind of packets and acts as
 * a FIFO; packets of a particular type are always retired in order.  But there
 * is no requirement about the order types are retired matching the original
 * order they arrived.
 * 
 * Gaps are tracked as just another kind of "packet" list.
 *
 * "allocations" (including gaps) are prepended by an lws_dsh_object_t.
 *
 * dsh may themselves be on an lws_dll2_owner list, and under memory pressure
 * allocate into other buffers on the list.
 *
 * All management structures exist inside the allocated buffer.
 */
 
enum {
        LWS_DSHFLAG_ENABLE_COALESCE                     = (1u << 24),
        LWS_DSHFLAG_ENABLE_SPLIT                        = (1u << 25),
};

LWS_VISIBLE LWS_EXTERN struct lws_dsh *
lws_dsh_create(lws_dll2_owner_t *owner, size_t buffer_size, int count_kinds);
 
LWS_VISIBLE LWS_EXTERN void
lws_dsh_empty(struct lws_dsh *dsh);

LWS_VISIBLE LWS_EXTERN void
lws_dsh_destroy(struct lws_dsh **pdsh);

LWS_VISIBLE LWS_EXTERN int
lws_dsh_alloc_tail(struct lws_dsh *dsh, int kind, const void *src1,
                   size_t size1, const void *src2, size_t size2);

LWS_VISIBLE LWS_EXTERN void
lws_dsh_free(void **obj);

LWS_VISIBLE LWS_EXTERN void
lws_dsh_consume(struct lws_dsh *dsh, int kind, size_t len);
 
LWS_VISIBLE LWS_EXTERN size_t
lws_dsh_get_size(struct lws_dsh *dsh, int kind);

LWS_VISIBLE LWS_EXTERN int
lws_dsh_get_head(struct lws_dsh *dsh, int kind, void **obj, size_t *size);

LWS_VISIBLE LWS_EXTERN void
lws_dsh_describe(struct lws_dsh *dsh, const char *desc);