478 lines
11 KiB
C++
478 lines
11 KiB
C++
/*
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* This file Copyright (C) 2010-2014 Mnemosyne LLC
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*
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* It may be used under the GNU GPL versions 2 or 3
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* or any future license endorsed by Mnemosyne LLC.
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*
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*/
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#include <stdlib.h> /* qsort() */
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#include <event2/buffer.h>
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#include "transmission.h"
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#include "cache.h"
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#include "inout.h"
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#include "log.h"
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#include "peer-common.h" /* MAX_BLOCK_SIZE */
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#include "ptrarray.h"
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#include "torrent.h"
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#include "tr-assert.h"
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#include "trevent.h"
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#include "utils.h"
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#define MY_NAME "Cache"
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#define dbgmsg(...) tr_logAddDeepNamed(MY_NAME, __VA_ARGS__)
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/****
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*****
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****/
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struct cache_block
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{
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tr_torrent* tor;
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tr_piece_index_t piece;
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uint32_t offset;
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uint32_t length;
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time_t time;
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tr_block_index_t block;
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struct evbuffer* evbuf;
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};
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struct tr_cache
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{
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tr_ptrArray blocks;
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int max_blocks;
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size_t max_bytes;
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size_t disk_writes;
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size_t disk_write_bytes;
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size_t cache_writes;
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size_t cache_write_bytes;
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};
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/****
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*****
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****/
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struct run_info
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{
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int pos;
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int rank;
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time_t last_block_time;
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bool is_multi_piece;
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bool is_piece_done;
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unsigned int len;
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};
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/* return a count of how many contiguous blocks there are starting at this pos */
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static int getBlockRun(tr_cache const* cache, int pos, struct run_info* info)
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{
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int const n = tr_ptrArraySize(&cache->blocks);
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struct cache_block const* const* blocks = (struct cache_block const* const*)tr_ptrArrayBase(&cache->blocks);
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struct cache_block const* ref = blocks[pos];
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tr_block_index_t block = ref->block;
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int len = 0;
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for (int i = pos; i < n; ++i)
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{
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struct cache_block const* b = blocks[i];
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if (b->block != block)
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{
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break;
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}
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if (b->tor != ref->tor)
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{
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break;
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}
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++block;
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++len;
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}
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if (info != nullptr)
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{
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struct cache_block const* b = blocks[pos + len - 1];
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info->last_block_time = b->time;
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info->is_piece_done = tr_torrentPieceIsComplete(b->tor, b->piece);
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info->is_multi_piece = b->piece != blocks[pos]->piece;
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info->len = len;
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info->pos = pos;
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}
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return len;
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}
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/* higher rank comes before lower rank */
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static int compareRuns(void const* va, void const* vb)
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{
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auto* a = static_cast<struct run_info const*>(va);
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auto* b = static_cast<struct run_info const*>(vb);
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return b->rank - a->rank;
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}
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enum
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{
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MULTIFLAG = 0x1000,
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DONEFLAG = 0x2000,
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SESSIONFLAG = 0x4000
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};
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/* Calculte runs
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* - Stale runs, runs sitting in cache for a long time or runs not growing, get priority.
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* Returns number of runs.
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*/
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static int calcRuns(tr_cache const* cache, struct run_info* runs)
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{
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int const n = tr_ptrArraySize(&cache->blocks);
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int i = 0;
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time_t const now = tr_time();
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for (int pos = 0; pos < n; pos += runs[i++].len)
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{
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int rank = getBlockRun(cache, pos, &runs[i]);
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/* This adds ~2 to the relative length of a run for every minute it has
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* languished in the cache. */
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rank += (now - runs[i].last_block_time) / 32;
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/* Flushing stale blocks should be a top priority as the probability of them
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* growing is very small, for blocks on piece boundaries, and nonexistant for
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* blocks inside pieces. */
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rank |= runs[i].is_piece_done ? DONEFLAG : 0;
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/* Move the multi piece runs higher */
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rank |= runs[i].is_multi_piece ? MULTIFLAG : 0;
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runs[i].rank = rank;
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}
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qsort(runs, i, sizeof(struct run_info), compareRuns);
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return i;
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}
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static int flushContiguous(tr_cache* cache, int pos, int n)
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{
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int err = 0;
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uint8_t* buf = tr_new(uint8_t, n * MAX_BLOCK_SIZE);
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uint8_t* walk = buf;
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struct cache_block** blocks = (struct cache_block**)tr_ptrArrayBase(&cache->blocks);
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struct cache_block* b = blocks[pos];
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tr_torrent* tor = b->tor;
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tr_piece_index_t const piece = b->piece;
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uint32_t const offset = b->offset;
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for (int i = 0; i < n; ++i)
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{
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b = blocks[pos + i];
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evbuffer_copyout(b->evbuf, walk, b->length);
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walk += b->length;
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evbuffer_free(b->evbuf);
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tr_free(b);
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}
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tr_ptrArrayErase(&cache->blocks, pos, pos + n);
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err = tr_ioWrite(tor, piece, offset, walk - buf, buf);
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tr_free(buf);
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++cache->disk_writes;
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cache->disk_write_bytes += walk - buf;
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return err;
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}
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static int flushRuns(tr_cache* cache, struct run_info* runs, int n)
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{
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int err = 0;
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for (int i = 0; err == 0 && i < n; i++)
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{
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err = flushContiguous(cache, runs[i].pos, runs[i].len);
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for (int j = i + 1; j < n; j++)
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{
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if (runs[j].pos > runs[i].pos)
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{
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runs[j].pos -= runs[i].len;
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}
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}
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}
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return err;
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}
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static int cacheTrim(tr_cache* cache)
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{
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int err = 0;
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if (tr_ptrArraySize(&cache->blocks) > cache->max_blocks)
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{
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/* Amount of cache that should be removed by the flush. This influences how large
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* runs can grow as well as how often flushes will happen. */
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int const cacheCutoff = 1 + cache->max_blocks / 4;
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struct run_info* runs = tr_new(struct run_info, tr_ptrArraySize(&cache->blocks));
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int i = 0;
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int j = 0;
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calcRuns(cache, runs);
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while (j < cacheCutoff)
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{
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j += runs[i++].len;
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}
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err = flushRuns(cache, runs, i);
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tr_free(runs);
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}
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return err;
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}
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/***
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****
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***/
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static int getMaxBlocks(int64_t max_bytes)
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{
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return max_bytes / (double)MAX_BLOCK_SIZE;
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}
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int tr_cacheSetLimit(tr_cache* cache, int64_t max_bytes)
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{
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char buf[128];
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cache->max_bytes = max_bytes;
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cache->max_blocks = getMaxBlocks(max_bytes);
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tr_formatter_mem_B(buf, cache->max_bytes, sizeof(buf));
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tr_logAddNamedDbg(MY_NAME, "Maximum cache size set to %s (%d blocks)", buf, cache->max_blocks);
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return cacheTrim(cache);
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}
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int64_t tr_cacheGetLimit(tr_cache const* cache)
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{
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return cache->max_bytes;
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}
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tr_cache* tr_cacheNew(int64_t max_bytes)
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{
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tr_cache* cache = tr_new0(tr_cache, 1);
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cache->blocks = {};
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cache->max_bytes = max_bytes;
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cache->max_blocks = getMaxBlocks(max_bytes);
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return cache;
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}
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void tr_cacheFree(tr_cache* cache)
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{
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TR_ASSERT(tr_ptrArrayEmpty(&cache->blocks));
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tr_ptrArrayDestruct(&cache->blocks, nullptr);
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tr_free(cache);
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}
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/***
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****
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***/
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static int cache_block_compare(void const* va, void const* vb)
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{
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auto const* a = static_cast<struct cache_block const*>(va);
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auto const* b = static_cast<struct cache_block const*>(vb);
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/* primary key: torrent id */
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if (a->tor->uniqueId != b->tor->uniqueId)
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{
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return a->tor->uniqueId < b->tor->uniqueId ? -1 : 1;
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}
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/* secondary key: block # */
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if (a->block != b->block)
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{
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return a->block < b->block ? -1 : 1;
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}
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/* they're equal */
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return 0;
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}
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static struct cache_block* findBlock(tr_cache* cache, tr_torrent* torrent, tr_piece_index_t piece, uint32_t offset)
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{
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struct cache_block key;
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key.tor = torrent;
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key.block = _tr_block(torrent, piece, offset);
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return static_cast<struct cache_block*>(tr_ptrArrayFindSorted(&cache->blocks, &key, cache_block_compare));
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}
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int tr_cacheWriteBlock(
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tr_cache* cache,
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tr_torrent* torrent,
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tr_piece_index_t piece,
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uint32_t offset,
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uint32_t length,
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struct evbuffer* writeme)
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{
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TR_ASSERT(tr_amInEventThread(torrent->session));
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struct cache_block* cb = findBlock(cache, torrent, piece, offset);
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if (cb == nullptr)
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{
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cb = tr_new(struct cache_block, 1);
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cb->tor = torrent;
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cb->piece = piece;
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cb->offset = offset;
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cb->length = length;
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cb->block = _tr_block(torrent, piece, offset);
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cb->evbuf = evbuffer_new();
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tr_ptrArrayInsertSorted(&cache->blocks, cb, cache_block_compare);
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}
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TR_ASSERT(cb->length == length);
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cb->time = tr_time();
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evbuffer_drain(cb->evbuf, evbuffer_get_length(cb->evbuf));
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evbuffer_remove_buffer(writeme, cb->evbuf, cb->length);
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cache->cache_writes++;
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cache->cache_write_bytes += cb->length;
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return cacheTrim(cache);
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}
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int tr_cacheReadBlock(
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tr_cache* cache,
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tr_torrent* torrent,
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tr_piece_index_t piece,
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uint32_t offset,
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uint32_t len,
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uint8_t* setme)
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{
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int err = 0;
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struct cache_block* cb = findBlock(cache, torrent, piece, offset);
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if (cb != nullptr)
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{
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evbuffer_copyout(cb->evbuf, setme, len);
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}
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else
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{
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err = tr_ioRead(torrent, piece, offset, len, setme);
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}
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return err;
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}
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int tr_cachePrefetchBlock(tr_cache* cache, tr_torrent* torrent, tr_piece_index_t piece, uint32_t offset, uint32_t len)
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{
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int err = 0;
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struct cache_block const* const cb = findBlock(cache, torrent, piece, offset);
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if (cb == nullptr)
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{
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err = tr_ioPrefetch(torrent, piece, offset, len);
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}
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return err;
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}
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/***
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****
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***/
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static int findBlockPos(tr_cache const* cache, tr_torrent* torrent, tr_piece_index_t block)
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{
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struct cache_block key;
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key.tor = torrent;
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key.block = block;
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return tr_ptrArrayLowerBound(&cache->blocks, &key, cache_block_compare, nullptr);
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}
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int tr_cacheFlushDone(tr_cache* cache)
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{
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int err = 0;
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if (tr_ptrArraySize(&cache->blocks) > 0)
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{
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int i;
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int n;
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struct run_info* runs;
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runs = tr_new(struct run_info, tr_ptrArraySize(&cache->blocks));
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i = 0;
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n = calcRuns(cache, runs);
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while (i < n && (runs[i].is_piece_done || runs[i].is_multi_piece))
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{
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runs[i++].rank |= SESSIONFLAG;
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}
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err = flushRuns(cache, runs, i);
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tr_free(runs);
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}
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return err;
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}
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int tr_cacheFlushFile(tr_cache* cache, tr_torrent* torrent, tr_file_index_t i)
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{
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int pos;
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int err = 0;
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tr_block_index_t first;
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tr_block_index_t last;
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tr_torGetFileBlockRange(torrent, i, &first, &last);
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pos = findBlockPos(cache, torrent, first);
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dbgmsg("flushing file %d from cache to disk: blocks [%zu...%zu]", (int)i, (size_t)first, (size_t)last);
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/* flush out all the blocks in that file */
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while (err == 0 && pos < tr_ptrArraySize(&cache->blocks))
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{
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auto const* b = static_cast<struct cache_block const*>(tr_ptrArrayNth(&cache->blocks, pos));
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if (b->tor != torrent)
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{
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break;
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}
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if (b->block < first || b->block > last)
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{
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break;
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}
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err = flushContiguous(cache, pos, getBlockRun(cache, pos, nullptr));
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}
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return err;
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}
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int tr_cacheFlushTorrent(tr_cache* cache, tr_torrent* torrent)
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{
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int err = 0;
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int const pos = findBlockPos(cache, torrent, 0);
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/* flush out all the blocks in that torrent */
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while (err == 0 && pos < tr_ptrArraySize(&cache->blocks))
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{
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auto const* b = static_cast<struct cache_block const*>(tr_ptrArrayNth(&cache->blocks, pos));
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if (b->tor != torrent)
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{
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break;
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}
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err = flushContiguous(cache, pos, getBlockRun(cache, pos, nullptr));
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}
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return err;
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}
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