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8d2b777fe3
This is where other imported components are located. All files which used to directly include ebtree were touched to update their include path so that "import/" is now prefixed before the ebtree-related files. The ebtree.h file was slightly adjusted to read compiler.h from the common/ subdirectory (this is the only change). A build issue was encountered when eb32sctree.h is loaded before eb32tree.h because only the former checks for the latter before defining type u32. This was addressed by adding the reverse ifdef in eb32tree.h. No further cleanup was done yet in order to keep changes minimal.
76 lines
3.7 KiB
C
76 lines
3.7 KiB
C
/*
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* Copyright (C) 2015 Willy Tarreau <w@1wt.eu>
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*
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* Permission is hereby granted, free of charge, to any person obtaining
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* a copy of this software and associated documentation files (the
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* "Software"), to deal in the Software without restriction, including
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* without limitation the rights to use, copy, modify, merge, publish,
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* distribute, sublicense, and/or sell copies of the Software, and to
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* permit persons to whom the Software is furnished to do so, subject to
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* the following conditions:
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*
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* The above copyright notice and this permission notice shall be
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* included in all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
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* OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
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* HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
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* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
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* OTHER DEALINGS IN THE SOFTWARE.
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*/
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#include <import/eb64tree.h>
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/* The LRU supports a global cache shared between multiple domains and multiple
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* versions of their datasets. The purpose is not to have to flush the whole
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* LRU once a key is updated and not valid anymore (eg: ACL files), as well as
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* to reliably support concurrent accesses and handle conflicts gracefully. For
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* each key a pointer to a dataset and its internal data revision are stored.
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* All lookups verify that these elements match those passed by the caller and
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* only return a valid entry upon matching. Otherwise the entry is either
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* allocated or recycled and considered new. New entries are always initialized
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* with a NULL domain pointer which is used by the caller to detect that the
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* entry is new and must be populated. Such entries never expire and are
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* protected from the risk of being recycled. It's then the caller's
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* responsibility to perform the operation and commit the entry with its latest
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* result. This domain thus serves as a lock to protect the entry during all
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* the computation needed to update it. In a simple use case where the cache is
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* dedicated, it is recommended to pass the LRU head as the domain pointer and
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* for example zero as the revision. The most common use case for the caller
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* consists in simply checking that the return is not null and that the domain
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* is not null, then to use the result. The get() function returns null if it
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* cannot allocate a node (memory or key being currently updated).
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*/
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struct lru64_list {
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struct lru64_list *n;
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struct lru64_list *p;
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};
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struct lru64_head {
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struct lru64_list list;
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struct eb_root keys;
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struct lru64 *spare;
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int cache_size;
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int cache_usage;
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};
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struct lru64 {
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struct eb64_node node; /* indexing key, typically a hash64 */
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struct lru64_list lru; /* LRU list */
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void *domain; /* who this data belongs to */
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unsigned long long revision; /* data revision (to avoid use-after-free) */
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void *data; /* returned value, user decides how to use this */
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void (*free)(void *data); /* function to release data, if needed */
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};
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struct lru64 *lru64_lookup(unsigned long long key, struct lru64_head *lru, void *domain, unsigned long long revision);
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struct lru64 *lru64_get(unsigned long long key, struct lru64_head *lru, void *domain, unsigned long long revision);
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void lru64_commit(struct lru64 *elem, void *data, void *domain, unsigned long long revision, void (*free)(void *));
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struct lru64_head *lru64_new(int size);
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int lru64_destroy(struct lru64_head *lru);
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void lru64_kill_oldest(struct lru64_head *lru, unsigned long int nb);
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