//===- InMemoryModuleCache.cpp - Cache for loaded memory buffers ----------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

#include "clang/Serialization/InMemoryModuleCache.h"
#include "clang/Basic/AtomicLineLogger.h"
#include "llvm/Support/MemoryBuffer.h"

using namespace clang;

InMemoryModuleCache::State
InMemoryModuleCache::getPCMState(llvm::StringRef Filename) const {
  auto I = PCMs.find(Filename);
  if (I == PCMs.end())
    return Unknown;
  if (I->second.IsFinal)
    return Final;
  return I->second.Buffer ? Tentative : ToBuild;
}

llvm::MemoryBuffer &
InMemoryModuleCache::addPCM(llvm::StringRef Filename,
                            std::unique_ptr<llvm::MemoryBuffer> Buffer,
                            off_t Size, time_t ModTime) {
  Logger.log() << "pcm_add: " << Filename;
  auto Insertion = PCMs.insert(
      std::make_pair(Filename, PCM(std::move(Buffer), Size, ModTime)));
  assert(Insertion.second && "Already has a PCM");
  return *Insertion.first->second.Buffer;
}

llvm::MemoryBuffer &
InMemoryModuleCache::addBuiltPCM(llvm::StringRef Filename,
                                 std::unique_ptr<llvm::MemoryBuffer> Buffer,
                                 off_t Size, time_t ModTime) {
  Logger.log() << "pcm_add_built: " << Filename;
  auto &PCM = PCMs[Filename];
  assert(!PCM.IsFinal && "Trying to override finalized PCM?");
  assert(!PCM.Buffer && "Trying to override tentative PCM?");
  PCM.Buffer = std::move(Buffer);
  PCM.Size = Size;
  PCM.ModTime = ModTime;
  PCM.IsFinal = true;
  return *PCM.Buffer;
}

llvm::MemoryBuffer *InMemoryModuleCache::lookupPCM(llvm::StringRef Filename,
                                                   off_t &Size,
                                                   time_t &ModTime) const {
  Logger.log() << "pcm_read_cached: " << Filename;
  auto I = PCMs.find(Filename);
  if (I == PCMs.end())
    return nullptr;
  Size = I->second.Size;
  ModTime = I->second.ModTime;
  return I->second.Buffer.get();
}

bool InMemoryModuleCache::isPCMFinal(llvm::StringRef Filename) const {
  return getPCMState(Filename) == Final;
}

bool InMemoryModuleCache::shouldBuildPCM(llvm::StringRef Filename) const {
  return getPCMState(Filename) == ToBuild;
}

bool InMemoryModuleCache::tryToDropPCM(llvm::StringRef Filename) {
  auto I = PCMs.find(Filename);
  assert(I != PCMs.end() && "PCM to remove is unknown...");

  auto &PCM = I->second;
  assert(PCM.Buffer && "PCM to remove is scheduled to be built...");

  if (PCM.IsFinal) {
    Logger.log() << "pcm_not_dropped: " << Filename;
    return true;
  }

  Logger.log() << "pcm_dropped: " << Filename;
  PCM.Buffer.reset();
  return false;
}

void InMemoryModuleCache::finalizePCM(llvm::StringRef Filename) {
  Logger.log() << "pcm_finalized: " << Filename;

  auto I = PCMs.find(Filename);
  assert(I != PCMs.end() && "PCM to finalize is unknown...");

  auto &PCM = I->second;
  assert(PCM.Buffer && "Trying to finalize a dropped PCM...");
  PCM.IsFinal = true;
}