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/* This file is part of the Spring engine (GPL v2 or later), see LICENSE.html */
#include <algorithm>
#include "PathCache.h"
#include "Sim/Misc/GlobalConstants.h"
#include "Sim/Misc/GlobalSynced.h"
#include "System/Log/ILog.h"
#define MAX_CACHE_QUEUE_SIZE 200
#define MAX_PATH_LIFETIME_SECS 6
#define USE_NONCOLLIDABLE_HASH 1
CPathCache::CPathCache(int blocksX, int blocksZ)
: numBlocksX(blocksX)
, numBlocksZ(blocksZ)
, numBlocks(numBlocksX * numBlocksZ)
, maxCacheSize(0)
, numCacheHits(0)
, numCacheMisses(0)
, numHashCollisions(0)
{
// {result, path, strtBlock, goalBlock, goalRadius, pathType}
dummyCacheItem = {IPath::Error, {}, {-1, -1}, {-1, -1}, -1.0f, -1};
cachedPaths.reserve(4096);
}
CPathCache::~CPathCache()
{
const char* fmt =
#ifdef _WIN32
"[%s(%ux%u)] cacheHits=%u hitPercentage=%.0f%% numHashColls=%u maxCacheSize=%I64u";
#else
"[%s(%ux%u)] cacheHits=%u hitPercentage=%.0f%% numHashColls=%u maxCacheSize=%lu";
#endif
LOG(fmt, __FUNCTION__, numBlocksX, numBlocksZ, numCacheHits, GetCacheHitPercentage(), numHashCollisions, maxCacheSize);
}
bool CPathCache::AddPath(
const IPath::Path* path,
const IPath::SearchResult result,
const int2 strtBlock,
const int2 goalBlock,
float goalRadius,
int pathType
) {
if (cacheQue.size() > MAX_CACHE_QUEUE_SIZE)
RemoveFrontQueItem();
const std::uint64_t hash = GetHash(strtBlock, goalBlock, goalRadius, pathType);
const std::uint32_t cols = numHashCollisions;
const auto iter = cachedPaths.find(hash);
// register any hash collisions
if (iter != cachedPaths.end())
return ((numHashCollisions += HashCollision(iter->second, strtBlock, goalBlock, goalRadius, pathType)) != cols);
cachedPaths[hash] = CacheItem{result, *path, strtBlock, goalBlock, goalRadius, pathType};
const int lifeTime = (result == IPath::Ok) ? GAME_SPEED * MAX_PATH_LIFETIME_SECS : GAME_SPEED * (MAX_PATH_LIFETIME_SECS / 2);
cacheQue.push_back({gs->frameNum + lifeTime, hash});
maxCacheSize = std::max<std::uint64_t>(maxCacheSize, cacheQue.size());
return false;
}
const CPathCache::CacheItem& CPathCache::GetCachedPath(
const int2 strtBlock,
const int2 goalBlock,
float goalRadius,
int pathType
) {
const std::uint64_t hash = GetHash(strtBlock, goalBlock, goalRadius, pathType);
const auto iter = cachedPaths.find(hash);
if (iter == cachedPaths.end()) {
++numCacheMisses; return dummyCacheItem;
}
if ((iter->second).strtBlock != strtBlock) {
++numCacheMisses; return dummyCacheItem;
}
if ((iter->second).goalBlock != goalBlock) {
++numCacheMisses; return dummyCacheItem;
}
if ((iter->second).pathType != pathType) {
++numCacheMisses; return dummyCacheItem;
}
++numCacheHits;
return (iter->second);
}
void CPathCache::Update()
{
while (!cacheQue.empty() && (cacheQue.front().timeout) < gs->frameNum)
RemoveFrontQueItem();
}
void CPathCache::RemoveFrontQueItem()
{
const auto it = cachedPaths.find((cacheQue.front()).hash);
assert(it != cachedPaths.end());
cachedPaths.erase(it);
cacheQue.pop_front();
}
std::uint64_t CPathCache::GetHash(
const int2 strtBlk,
const int2 goalBlk,
std::uint32_t goalRadius,
std::int32_t pathType
) const {
#define N numBlocks
#define NX numBlocksX
#define NZ numBlocksZ
#ifndef USE_NONCOLLIDABLE_HASH
// susceptible to collisions for given pathType and goalRadius:
// Hash(sb=< 8,18> gb=<17, 2> ...)==Hash(sb=< 9,18> gb=<15, 2> ...)
// Hash(sb=<11,10> gb=<17, 1> ...)==Hash(sb=<12,10> gb=<15, 1> ...)
// Hash(sb=<12,10> gb=<17, 2> ...)==Hash(sb=<13,10> gb=<15, 2> ...)
// Hash(sb=<13,10> gb=<15, 1> ...)==Hash(sb=<12,10> gb=<17, 1> ...)
// Hash(sb=<13,10> gb=<15, 3> ...)==Hash(sb=<12,10> gb=<17, 3> ...)
// Hash(sb=<12,18> gb=< 6,28> ...)==Hash(sb=<11,18> gb=< 8,28> ...)
//
const std::uint32_t index = ((goalBlk.y * NX + goalBlk.x) * NZ + strtBlk.y) * NX;
const std::uint32_t offset = strtBlk.x * (pathType + 1) * std::max(1.0f, goalRadius);
return (index + offset);
#else
// map into linear space, cannot collide unless given non-integer radii
const std::uint64_t index =
(strtBlk.y * NX + strtBlk.x) +
(goalBlk.y * NX + goalBlk.x) * N;
const std::uint64_t offset =
pathType * N*N +
goalRadius * N*N*N;
return (index + offset);
#endif
#undef NZ
#undef NX
#undef N
}
bool CPathCache::HashCollision(
const CacheItem& ci,
const int2 strtBlk,
const int2 goalBlk,
float goalRadius,
int pathType
) const {
bool hashColl = false;
hashColl |= (ci.strtBlock != strtBlk || ci.goalBlock != goalBlk);
hashColl |= (ci.pathType != pathType || ci.goalRadius != goalRadius);
const char* fmt =
#ifdef _WIN32
"[%s][f=%d][hash=%I64u] Hash(sb=<%d,%d> gb=<%d,%d> gr=%.2f pt=%d)==Hash(sb=<%d,%d> gb=<%d,%d> gr=%.2f pt=%d)";
#else
"[%s][f=%d][hash=%lu] Hash(sb=<%d,%d> gb=<%d,%d> gr=%.2f pt=%d)==Hash(sb=<%d,%d> gb=<%d,%d> gr=%.2f pt=%d)";
#endif
if (hashColl) {
LOG_L(L_DEBUG, fmt,
__FUNCTION__, gs->frameNum,
GetHash(strtBlk, goalBlk, goalRadius, pathType),
ci.strtBlock.x, ci.strtBlock.y,
ci.goalBlock.x, ci.goalBlock.y,
ci.goalRadius, ci.pathType,
strtBlk.x, strtBlk.y,
goalBlk.x, goalBlk.y,
goalRadius, pathType
);
}
return hashColl;
}
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