Skip memory caches in JitDebug interface

The JitDebug interface relies on being able to re-read memory to
see the latest entries and to do cross-process synchronization.

Test: Run ART gcstress tests manually
Change-Id: Ic4aca458a6b013265f573aa84f4a11822ec5cefb

3 files changed, 18 insertions, 1 deletions

diff --git a/libunwindstack/GlobalDebugImpl.h b/libunwindstack/GlobalDebugImpl.h
index be7d40c..5ba772c 100644
--- a/libunwindstack/GlobalDebugImpl.h
+++ b/libunwindstack/GlobalDebugImpl.h
@@ -29,6 +29,7 @@
 
 #include "Check.h"
 #include "GlobalDebugInterface.h"
+#include "MemoryCache.h"
 #include "MemoryRange.h"
 
 // This implements the JIT Compilation Interface.
@@ -362,6 +363,14 @@ std::unique_ptr<GlobalDebugInterface<Symfile>> CreateGlobalDebugImpl(
     ArchEnum arch, std::shared_ptr<Memory>& memory, std::vector<std::string> search_libs,
     const char* global_variable_name) {
   CHECK(arch != ARCH_UNKNOWN);
+
+  // The interface needs to see real-time changes in memory for synchronization with the
+  // concurrently running ART JIT compiler. Skip caching and read the memory directly.
+  MemoryCacheBase* cached_memory = memory->AsMemoryCacheBase();
+  if (cached_memory != nullptr) {
+    memory = cached_memory->UnderlyingMemory();
+  }
+
   switch (arch) {
     case ARCH_X86: {
       using Impl = GlobalDebugImpl<Symfile, uint32_t, Uint64_P>;
diff --git a/libunwindstack/MemoryCache.h b/libunwindstack/MemoryCache.h
index ebc8708..523a4a1 100644
--- a/libunwindstack/MemoryCache.h
+++ b/libunwindstack/MemoryCache.h
@@ -34,6 +34,10 @@ class MemoryCacheBase : public Memory {
   MemoryCacheBase(Memory* memory) : impl_(memory) {}
   virtual ~MemoryCacheBase() = default;
 
+  MemoryCacheBase* AsMemoryCacheBase() override { return this; }
+
+  const std::shared_ptr<Memory>& UnderlyingMemory() { return impl_; }
+
   size_t Read(uint64_t addr, void* dst, size_t size) override {
     // Only look at the cache for small reads.
     if (size > 64) {
@@ -55,7 +59,7 @@ class MemoryCacheBase : public Memory {
 
   size_t InternalCachedRead(uint64_t addr, void* dst, size_t size, CacheDataType* cache);
 
-  std::unique_ptr<Memory> impl_;
+  std::shared_ptr<Memory> impl_;
 };
 
 class MemoryCache : public MemoryCacheBase {
diff --git a/libunwindstack/include/unwindstack/Memory.h b/libunwindstack/include/unwindstack/Memory.h
index c719544..b7bede6 100644
--- a/libunwindstack/include/unwindstack/Memory.h
+++ b/libunwindstack/include/unwindstack/Memory.h
@@ -26,6 +26,8 @@
 
 namespace unwindstack {
 
+class MemoryCacheBase;
+
 class Memory {
  public:
   Memory() = default;
@@ -39,6 +41,8 @@ class Memory {
   static std::unique_ptr<Memory> CreateFileMemory(const std::string& path, uint64_t offset,
                                                   uint64_t size = UINT64_MAX);
 
+  virtual MemoryCacheBase* AsMemoryCacheBase() { return nullptr; }
+
   virtual bool ReadString(uint64_t addr, std::string* dst, size_t max_read);
 
   virtual void Clear() {}