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CostManager: introduce a free-list of ~10 intervals

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and also recycle the malloc'd intervals
This avoids quite some malloc/free cycles during interval managment.

Change-Id: Ic2892e7c0260d0fca0e455d4728f261fb4c3800e
This commit is contained in:
Pascal Massimino 2016-06-08 16:31:23 +02:00
parent 0481d42ad8
commit eab39d8147
1 changed files with 59 additions and 24 deletions
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83
src/enc/backward_references.c
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@ -611,6 +611,7 @@ typedef struct {
// It caches the different CostCacheInterval, caches the different
// GetLengthCost(cost_model, k) in cost_cache_ and the CostInterval's (whose
// count_ is limited by COST_CACHE_INTERVAL_SIZE_MAX).
#define COST_MANAGER_MAX_FREE_LIST 10
typedef struct {
CostInterval* head_;
int count_; // The number of stored intervals.
@ -619,8 +620,13 @@ typedef struct {
double cost_cache_[MAX_LENGTH]; // Contains the GetLengthCost(cost_model, k).
float* costs_;
uint16_t* dist_array_;
CostInterval spare_; // most of the time, we only will be using a single
int spare_used_; // interval. => We re-use this one first if possible.
// Most of the time, we only need few intervals -> use a free-list, to avoid
// fragmentation with small allocs in most common cases.
CostInterval intervals_[COST_MANAGER_MAX_FREE_LIST];
CostInterval* free_intervals_;
// These are regularly malloc'd remains. This list can't grow larger than than
// size COST_CACHE_INTERVAL_SIZE_MAX - COST_MANAGER_MAX_FREE_LIST, note.
CostInterval* recycled_intervals_;
} CostManager;
static int IsCostCacheIntervalWritable(int start, int end) {
@ -633,28 +639,52 @@ static int IsCostCacheIntervalWritable(int start, int end) {
return (end - start + 1 < 100);
}
static void CostIntervalAddToFreeList(CostManager* const manager,
CostInterval* const interval) {
interval->next_ = manager->free_intervals_;
manager->free_intervals_ = interval;
}
static int CostIntervalIsInFreeList(const CostManager* const manager,
const CostInterval* const interval) {
return (interval >= &manager->intervals_[0] &&
interval <= &manager->intervals_[COST_MANAGER_MAX_FREE_LIST - 1]);
}
static void CostManagerInitFreeList(CostManager* const manager) {
int i;
manager->free_intervals_ = NULL;
for (i = 0; i < COST_MANAGER_MAX_FREE_LIST; ++i) {
CostIntervalAddToFreeList(manager, &manager->intervals_[i]);
}
}
static void DeleteIntervalList(CostManager* const manager,
const CostInterval* interval) {
while (interval != NULL) {
const CostInterval* const next = interval->next_;
if (!CostIntervalIsInFreeList(manager, interval)) {
WebPSafeFree((void*)interval);
} // else: do nothing
interval = next;
}
}
static void CostManagerClear(CostManager* const manager) {
if (manager == NULL) return;
WebPSafeFree(manager->costs_);
WebPSafeFree(manager->cache_intervals_);
// Clear the intervals.
{
CostInterval* interval = manager->head_;
while (interval != NULL) {
CostInterval* const next = interval->next_;
if (manager->spare_used_ && interval == &manager->spare_) {
manager->spare_used_ = 0;
} else {
WebPSafeFree(interval);
}
interval = next;
}
}
// Clear the interval lists.
DeleteIntervalList(manager, manager->head_);
manager->head_ = NULL;
DeleteIntervalList(manager, manager->recycled_intervals_);
manager->recycled_intervals_ = NULL;
// Reset pointers, count_ and cache_intervals_size_.
memset(manager, 0, sizeof(*manager));
CostManagerInitFreeList(manager);
}
static int CostManagerInit(CostManager* const manager,
@ -667,9 +697,10 @@ static int CostManagerInit(CostManager* const manager,
const double min_cost_diff = 0.1;
manager->head_ = NULL;
manager->recycled_intervals_ = NULL;
manager->count_ = 0;
manager->dist_array_ = dist_array;
manager->spare_used_ = 0;
CostManagerInitFreeList(manager);
// Fill in the cost_cache_.
manager->cache_intervals_size_ = 1;
@ -800,10 +831,11 @@ static WEBP_INLINE void PopInterval(CostManager* const manager,
if (interval == NULL) return;
ConnectIntervals(manager, interval->previous_, next);
if (interval == &manager->spare_) {
manager->spare_used_ = 0;
} else {
WebPSafeFree(interval);
if (CostIntervalIsInFreeList(manager, interval)) {
CostIntervalAddToFreeList(manager, interval);
} else { // recycle regularly malloc'd intervals too
interval->next_ = manager->recycled_intervals_;
manager->recycled_intervals_ = interval;
}
--manager->count_;
assert(manager->count_ >= 0);
@ -867,10 +899,13 @@ static WEBP_INLINE void InsertInterval(CostManager* const manager,
UpdateCostPerInterval(manager, start, end, index, distance_cost);
return;
}
if (!manager->spare_used_) {
interval_new = &manager->spare_;
manager->spare_used_ = 1;
} else {
if (manager->free_intervals_ != NULL) {
interval_new = manager->free_intervals_;
manager->free_intervals_ = interval_new->next_;
} else if (manager->recycled_intervals_ != NULL) {
interval_new = manager->recycled_intervals_;
manager->recycled_intervals_ = interval_new->next_;
} else { // malloc for good
interval_new = (CostInterval*)WebPSafeMalloc(1, sizeof(*interval_new));
if (interval_new == NULL) {
// Write down the interval if we cannot create it.