/*
 * Copyright 2022 Google LLC
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#include "src/gpu/graphite/GlobalCache.h"

#include "include/private/base/SkTArray.h"
#include "src/core/SkTraceEvent.h"
#include "src/gpu/graphite/ComputePipeline.h"
#include "src/gpu/graphite/ContextUtils.h"
#include "src/gpu/graphite/GraphicsPipeline.h"
#include "src/gpu/graphite/GraphicsPipelineDesc.h"
#include "src/gpu/graphite/RenderPassDesc.h"
#include "src/gpu/graphite/Resource.h"
#include "src/gpu/graphite/SharedContext.h"

#if defined(SK_ENABLE_PRECOMPILE)
#include "src/gpu/graphite/precompile/SerializationUtils.h"
#endif

namespace {

uint32_t next_compilation_id() {
    static std::atomic<uint32_t> nextId{0};
    // Not worried about overflow since we don't expect that many GraphicsPipelines.
    // Even if it wraps around to 0, this is solely for debug logging.
    return nextId.fetch_add(1, std::memory_order_relaxed);
}

#if defined(GPU_TEST_UTILS)
// TODO(b/391403921): get rid of this special case once we've got color space transform shader
// specialization more under control
constexpr int kGlobalGraphicsPipelineCacheSizeLimit = 1 << 13;
constexpr int kGlobalComputePipelineCacheSizeLimit = 256;

#else
// TODO: find a good value for these limits
constexpr int kGlobalGraphicsPipelineCacheSizeLimit = 256;
constexpr int kGlobalComputePipelineCacheSizeLimit = 256;
#endif

} // anonymous namespce

namespace skgpu::graphite {

GlobalCache::GlobalCache()
        : fGraphicsPipelineCache(kGlobalGraphicsPipelineCacheSizeLimit, &fStats)
        , fComputePipelineCache(kGlobalComputePipelineCacheSizeLimit) {}

GlobalCache::~GlobalCache() {
    // These should have been cleared out earlier by deleteResources().
    SkDEBUGCODE(SkAutoSpinlock lock{ fSpinLock });
    SkASSERT(fGraphicsPipelineCache.count() == 0);
    SkASSERT(fComputePipelineCache.count() == 0);
    SkASSERT(fStaticResource.empty());
}

void GlobalCache::setPipelineCallback(PipelineCallback callback, PipelineCallbackContext context) {
    SkAutoSpinlock lock{fSpinLock};

    fPipelineCallback = callback;
    fPipelineCallbackContext = context;
}

void GlobalCache::invokePipelineCallback(SharedContext* sharedContext,
                                         const GraphicsPipelineDesc& pipelineDesc,
                                         const RenderPassDesc& renderPassDesc) {
#if defined(SK_ENABLE_PRECOMPILE)
    PipelineCallback tmpCB = nullptr;
    PipelineCallbackContext tmpContext = nullptr;

    {
        // We want to get a consistent callback/context pair but not invoke the callback
        // w/in our lock.
        SkAutoSpinlock lock{fSpinLock};

        tmpCB = fPipelineCallback;
        tmpContext = fPipelineCallbackContext;
    }

    if (tmpCB) {
        sk_sp<SkData> data = PipelineDescToData(sharedContext->shaderCodeDictionary(),
                                                pipelineDesc,
                                                renderPassDesc);

        // Enable this to thoroughly test Pipeline serialization
#if 0
        {
            // Check that the PipelineDesc round trips through serialization
            GraphicsPipelineDesc readBackPipelineDesc;
            RenderPassDesc readBackRenderPassDesc;

            SkAssertResult(DataToPipelineDesc(sharedContext->caps(),
                                              sharedContext->shaderCodeDictionary(),
                                              data.get(),
                                              &readBackPipelineDesc,
                                              &readBackRenderPassDesc));

            DumpPipelineDesc("invokeCallback - original", sharedContext->shaderCodeDictionary(),
                             pipelineDesc, renderPassDesc);

            DumpPipelineDesc("invokeCallback - readback", sharedContext->shaderCodeDictionary(),
                  readBackPipelineDesc, readBackRenderPassDesc);

            SkASSERT(ComparePipelineDescs(pipelineDesc, renderPassDesc,
                                          readBackPipelineDesc, readBackRenderPassDesc));
        }
#endif

        if (data) {
            tmpCB(tmpContext, std::move(data));
        }
    }
#endif
}

void GlobalCache::deleteResources() {
    SkAutoSpinlock lock{ fSpinLock };

    fGraphicsPipelineCache.reset();
    fComputePipelineCache.reset();
    fStaticResource.clear();
}

void GlobalCache::LogPurge(void* context, const UniqueKey& key, sk_sp<GraphicsPipeline>* p) {
    PipelineStats* stats = static_cast<PipelineStats*>(context);

    if ((*p)->fromPrecompile() && !(*p)->wasUsed()) {
        ++stats->fPurgedUnusedPrecompiledPipelines;
    }

#if defined(SK_PIPELINE_LIFETIME_LOGGING)
    // A "Bad" Purge is one where the Pipeline was never retrieved from the Cache (i.e., unused
    // overgeneration).
    static const char* kNames[2][2] = { { "BadPurgedN", "BadPurgedP" },
                                        { "PurgedN",    "PurgedP"} };

    TRACE_EVENT_INSTANT2("skia.gpu",
                         TRACE_STR_STATIC(kNames[(*p)->wasUsed()][(*p)->fromPrecompile()]),
                         TRACE_EVENT_SCOPE_THREAD,
                         "key", key.hash(),
                         "compilationID", (*p)->getPipelineInfo().fCompilationID);
#endif
}

sk_sp<GraphicsPipeline> GlobalCache::findGraphicsPipeline(
        const UniqueKey& key,
        SkEnumBitMask<PipelineCreationFlags> pipelineCreationFlags,
        uint32_t *compilationID) {

    [[maybe_unused]] bool forPrecompile =
            SkToBool(pipelineCreationFlags & PipelineCreationFlags::kForPrecompilation);

    SkAutoSpinlock lock{fSpinLock};

    sk_sp<GraphicsPipeline>* entry = fGraphicsPipelineCache.find(key);
    if (entry) {
#if defined(GPU_TEST_UTILS)
        ++fStats.fGraphicsCacheHits;
#endif

        if ((*entry)->epoch() != fEpochCounter) {
            (*entry)->markEpoch(fEpochCounter);   // update epoch due to use in a new epoch
            ++fStats.fPipelineUsesInEpoch;
        }
        if (!forPrecompile && (*entry)->fromPrecompile() && !(*entry)->wasUsed()) {
            ++fStats.fNormalPreemptedByPrecompile;
        }

        (*entry)->updateAccessTime();
        (*entry)->markUsed();

#if defined(SK_PIPELINE_LIFETIME_LOGGING)
        static const char* kNames[2] = { "CacheHitForN", "CacheHitForP" };
        TRACE_EVENT_INSTANT2("skia.gpu",
                             TRACE_STR_STATIC(kNames[forPrecompile]),
                             TRACE_EVENT_SCOPE_THREAD,
                             "key", key.hash(),
                             "compilationID", (*entry)->getPipelineInfo().fCompilationID);
#endif

        return *entry;
    } else {
#if defined(GPU_TEST_UTILS)
        ++fStats.fGraphicsCacheMisses;
#endif

        if (compilationID) {
            // This is a cache miss so we know the next step is going to be a Pipeline
            // creation. Create the compilationID here so we can use it in the "CacheMissFor"
            // trace event.
            *compilationID = next_compilation_id();

#if defined(SK_PIPELINE_LIFETIME_LOGGING)
            static const char* kNames[2] = { "CacheMissForN", "CacheMissForP" };
            TRACE_EVENT_INSTANT2("skia.gpu",
                                 TRACE_STR_STATIC(kNames[forPrecompile]),
                                 TRACE_EVENT_SCOPE_THREAD,
                                 "key", key.hash(),
                                 "compilationID", *compilationID);
#endif
        }

        return nullptr;
    }
}

#if SK_HISTOGRAMS_ENABLED
// These values are persisted to logs. Entries should not be renumbered and
// numeric values should never be reused.
//
// LINT.IfChange(PipelineCreationRace)
enum class PipelineCreationRace {
    // The <First>Over<Second> enum names mean the first type of compilation won a compilation race
    // over the second type of compilation and ended up in the cache.
    kNormalOverNormal                 = 0, // can happen w/ multiple Recorders on different threads
    kNormalOverPrecompilation         = 1,
    kPrecompilationOverNormal         = 2,
    kPrecompilationOverPrecompilation = 3, // can happen with multiple threaded precompilation calls

    kMaxValue = kPrecompilationOverPrecompilation,
};
// LINT.ThenChange(//tools/metrics/histograms/enums.xml:SkiaPipelineCreationRace)

[[maybe_unused]] static constexpr int kPipelineCreationRaceCount =
        static_cast<int>(PipelineCreationRace::kMaxValue) + 1;
#endif // SK_HISTOGRAMS_ENABLED

sk_sp<GraphicsPipeline> GlobalCache::addGraphicsPipeline(const UniqueKey& key,
                                                         sk_sp<GraphicsPipeline> pipeline) {
    SkAutoSpinlock lock{fSpinLock};

    sk_sp<GraphicsPipeline>* entry = fGraphicsPipelineCache.find(key);
    if (!entry) {
        // No equivalent pipeline was stored in the cache between a previous call to
        // findGraphicsPipeline() that returned null (triggering the pipeline creation) and this
        // later adding to the cache.
        entry = fGraphicsPipelineCache.insert(key, std::move(pipeline));

#if defined(GPU_TEST_UTILS)
        ++fStats.fGraphicsCacheAdditions;
#endif

        SkASSERT((*entry)->epoch() == 0);
        (*entry)->markEpoch(fEpochCounter);      // mark w/ epoch in which it was created
        ++fStats.fPipelineUsesInEpoch;

        if ((*entry)->fromPrecompile()) {
            ++fStats.fUnpreemptedPrecompilePipelines;
        }

        // Precompile Pipelines are only marked as used when they get a cache hit in
        // findGraphicsPipeline
        if (!(*entry)->fromPrecompile()) {
            (*entry)->updateAccessTime();
            (*entry)->markUsed();
        }

#if defined(SK_PIPELINE_LIFETIME_LOGGING)
        static const char* kNames[2] = { "AddedN", "AddedP" };
        TRACE_EVENT_INSTANT2("skia.gpu",
                             TRACE_STR_STATIC(kNames[(*entry)->fromPrecompile()]),
                             TRACE_EVENT_SCOPE_THREAD,
                             "key", key.hash(),
                             "compilationID", (*entry)->getPipelineInfo().fCompilationID);
#endif
    } else {
#if defined(GPU_TEST_UTILS)
        // else there was a race creating the same pipeline and this thread lost, so return
        // the winner
        ++fStats.fGraphicsRaces;
#endif

        [[maybe_unused]] int race = (*entry)->fromPrecompile() * 2 + pipeline->fromPrecompile();

#if defined(SK_PIPELINE_LIFETIME_LOGGING)
        static const char* kNames[4] = {
                "NWonRaceOverN",
                "NWonRaceOverP",
                "PWonRaceOverN",
                "PWonRaceOverP"
        };
        TRACE_EVENT_INSTANT2("skia.gpu",
                             TRACE_STR_STATIC(kNames[race]),
                             TRACE_EVENT_SCOPE_THREAD,
                             "key", key.hash(),
                             // The losing compilation
                             "compilationID", pipeline->getPipelineInfo().fCompilationID);
#endif

        SK_HISTOGRAM_ENUMERATION("Graphite.PipelineCreationRace",
                                 race,
                                 kPipelineCreationRaceCount);
    }
    return *entry;
}

void GlobalCache::removeGraphicsPipeline(const GraphicsPipeline* pipeline) {
    SkAutoSpinlock lock{fSpinLock};

    skia_private::STArray<1, skgpu::UniqueKey> toRemove;
    // This is only called when a pipeline failed to compile, so it is not performance critical.
    fGraphicsPipelineCache.foreach([&toRemove, pipeline](const UniqueKey* key,
                                                         const sk_sp<GraphicsPipeline>* inCache) {
        // Since inCache is ref'ed by GlobalCache, we can safely compare direct addresses and not
        // worry about a new GraphicsPipeline being allocated at an address that was still here.
        if ((*inCache).get() == pipeline) {
            toRemove.push_back(*key);
        }
    });

    // The pipeline shouldn't have multiple unique keys, but this is structured to clean up every
    // occurrence of pipeline in fGraphicsPipelineCache in release builds.
    SkASSERT(toRemove.size() <= 1);

    for (const skgpu::UniqueKey& k : toRemove) {
        fGraphicsPipelineCache.remove(k);
    }
}

void GlobalCache::purgePipelinesNotUsedSince(StdSteadyClock::time_point purgeTime) {
    SkAutoSpinlock lock{fSpinLock};

    skia_private::TArray<skgpu::UniqueKey> toRemove;

    // This is probably fine for now but is looping from most-recently-used to least-recently-used.
    // It seems like a reverse loop with an early out could be more efficient.
    fGraphicsPipelineCache.foreach([&toRemove, purgeTime](const UniqueKey* key,
                                                          const sk_sp<GraphicsPipeline>* pipeline) {
        if ((*pipeline)->lastAccessTime() < purgeTime) {
            toRemove.push_back(*key);
        }
    });

    for (const skgpu::UniqueKey& k : toRemove) {
#if defined(GPU_TEST_UTILS)
        ++fStats.fGraphicsPurges;
#endif
        fGraphicsPipelineCache.remove(k);
    }

    // TODO: add purging of Compute Pipelines (b/389073204)
}

void GlobalCache::reportPrecompileStats() {
    SkAutoSpinlock lock{fSpinLock};

    uint32_t numUnusedInCache = 0;

    fGraphicsPipelineCache.foreach([&numUnusedInCache](const UniqueKey* key,
                                                       const sk_sp<GraphicsPipeline>* pipeline) {
        if (!(*pipeline)->wasUsed()) {
            SkASSERT((*pipeline)->fromPrecompile());
            ++numUnusedInCache;
        }
    });

    // From local testing we expect these UMA stats to comfortably fit in the specified ranges.
    // If we see a lot of the counts hitting the over and under-flow buckets something
    // unexpected is happening and we would need to figure it out and, possibly, create
    // new UMA statistics for the observed range.
    SK_HISTOGRAM_CUSTOM_EXACT_LINEAR("Graphite.Precompile.NormalPreemptedByPrecompile",
                                     fStats.fNormalPreemptedByPrecompile,
                                     /* countMin= */ 1,
                                     /* countMax= */ 51,
                                     /* bucketCount= */ 52);
    SK_HISTOGRAM_CUSTOM_EXACT_LINEAR("Graphite.Precompile.UnpreemptedPrecompilePipelines",
                                     fStats.fUnpreemptedPrecompilePipelines,
                                     /* countMin= */ 100,
                                     /* countMax= */ 150,
                                     /* bucketCount= */ 52);
    SK_HISTOGRAM_CUSTOM_EXACT_LINEAR("Graphite.Precompile.UnusedPrecompiledPipelines",
                                     fStats.fPurgedUnusedPrecompiledPipelines + numUnusedInCache,
                                     /* countMin= */ 50,
                                     /* countMax= */ 100,
                                     /* bucketCount= */ 52);
}

void GlobalCache::reportCacheStats() {
    SkAutoSpinlock lock{fSpinLock};

    SK_HISTOGRAM_CUSTOM_EXACT_LINEAR("Graphite.PipelineCache.PipelineUsesInEpoch",
                                     fStats.fPipelineUsesInEpoch,
                                     /* countMin= */ 1,
                                     /* countMax= */ 1001,
                                     /* bucketCount= */ 102); // 10/bucket

    // Set up for a new epoch
    fStats.fPipelineUsesInEpoch = 0;
    ++fEpochCounter;
    if (!fEpochCounter) {
        // The epoch counter has wrapped around - this should be *very* rare. Reset the cache.
        fGraphicsPipelineCache.foreach([](const UniqueKey* key,
                                          const sk_sp<GraphicsPipeline>* pipeline) {
            (*pipeline)->markEpoch(0);
        });
        fEpochCounter = 1;
    }
}

#if defined(GPU_TEST_UTILS)
int GlobalCache::numGraphicsPipelines() const {
    SkAutoSpinlock lock{fSpinLock};

    return fGraphicsPipelineCache.count();
}

void GlobalCache::resetGraphicsPipelines() {
    SkAutoSpinlock lock{fSpinLock};

    fGraphicsPipelineCache.reset();
}

void GlobalCache::forEachGraphicsPipeline(
        const std::function<void(const UniqueKey&, const GraphicsPipeline*)>& fn) {
    SkAutoSpinlock lock{fSpinLock};

    fGraphicsPipelineCache.foreach([&](const UniqueKey* k, const sk_sp<GraphicsPipeline>* v) {
        fn(*k, v->get());
    });
}

uint16_t GlobalCache::getEpoch() const {
    SkAutoSpinlock lock{fSpinLock};

    return fEpochCounter;
}

// The next reportCacheStats call after this will overflow
void GlobalCache::forceNextEpochOverflow() {
    SkAutoSpinlock lock{fSpinLock};

    fEpochCounter = std::numeric_limits<uint16_t>::max();
}

#endif // defined(GPU_TEST_UTILS)

GlobalCache::PipelineStats GlobalCache::getStats() const {
    SkAutoSpinlock lock{fSpinLock};

    return fStats;
}

sk_sp<ComputePipeline> GlobalCache::findComputePipeline(const UniqueKey& key) {
    SkAutoSpinlock lock{fSpinLock};
    sk_sp<ComputePipeline>* entry = fComputePipelineCache.find(key);
    return entry ? *entry : nullptr;
}

sk_sp<ComputePipeline> GlobalCache::addComputePipeline(const UniqueKey& key,
                                                       sk_sp<ComputePipeline> pipeline) {
    SkAutoSpinlock lock{fSpinLock};
    sk_sp<ComputePipeline>* entry = fComputePipelineCache.find(key);
    if (!entry) {
        entry = fComputePipelineCache.insert(key, std::move(pipeline));
    }
    return *entry;
}

void GlobalCache::addStaticResource(sk_sp<Resource> resource) {
    SkAutoSpinlock lock{fSpinLock};
    fStaticResource.push_back(std::move(resource));
}

} // namespace skgpu::graphite