Improve profile processing

- allow file descriptors in addition to file names for profiles
- fix some minor issues (wrong comparison signs, unhandled errors)
- added gtests for profile_compilation_info, profile_assistant
and compiler_driver

Bug: 26080105
Change-Id: I136039fa1f25858399000049e48b01eafae54eb1
diff --git a/runtime/base/scoped_flock.cc b/runtime/base/scoped_flock.cc
index 71e0590..814cbd0 100644
--- a/runtime/base/scoped_flock.cc
+++ b/runtime/base/scoped_flock.cc
@@ -26,16 +26,25 @@
 namespace art {
 
 bool ScopedFlock::Init(const char* filename, std::string* error_msg) {
+  return Init(filename, O_CREAT | O_RDWR, true, error_msg);
+}
+
+bool ScopedFlock::Init(const char* filename, int flags, bool block, std::string* error_msg) {
   while (true) {
     if (file_.get() != nullptr) {
       UNUSED(file_->FlushCloseOrErase());  // Ignore result.
     }
-    file_.reset(OS::OpenFileWithFlags(filename, O_CREAT | O_RDWR));
+    file_.reset(OS::OpenFileWithFlags(filename, flags));
     if (file_.get() == nullptr) {
       *error_msg = StringPrintf("Failed to open file '%s': %s", filename, strerror(errno));
       return false;
     }
-    int flock_result = TEMP_FAILURE_RETRY(flock(file_->Fd(), LOCK_EX));
+    int operation = block ? LOCK_EX : (LOCK_EX | LOCK_NB);
+    int flock_result = TEMP_FAILURE_RETRY(flock(file_->Fd(), operation));
+    if (flock_result == EWOULDBLOCK) {
+      // File is locked by someone else and we are required not to block;
+      return false;
+    }
     if (flock_result != 0) {
       *error_msg = StringPrintf("Failed to lock file '%s': %s", filename, strerror(errno));
       return false;
@@ -51,11 +60,23 @@
     if (stat_result != 0) {
       PLOG(WARNING) << "Failed to stat, will retry: " << filename;
       // ENOENT can happen if someone racing with us unlinks the file we created so just retry.
-      continue;
+      if (block) {
+        continue;
+      } else {
+        // Note that in theory we could race with someone here for a long time and end up retrying
+        // over and over again. This potential behavior does not fit well in the non-blocking
+        // semantics. Thus, if we are not require to block return failure when racing.
+        return false;
+      }
     }
     if (fstat_stat.st_dev != stat_stat.st_dev || fstat_stat.st_ino != stat_stat.st_ino) {
       LOG(WARNING) << "File changed while locking, will retry: " << filename;
-      continue;
+      if (block) {
+        continue;
+      } else {
+        // See comment above.
+        return false;
+      }
     }
     return true;
   }
@@ -78,7 +99,7 @@
   return true;
 }
 
-File* ScopedFlock::GetFile() {
+File* ScopedFlock::GetFile() const {
   CHECK(file_.get() != nullptr);
   return file_.get();
 }
diff --git a/runtime/base/scoped_flock.h b/runtime/base/scoped_flock.h
index 08612e3..cc22056 100644
--- a/runtime/base/scoped_flock.h
+++ b/runtime/base/scoped_flock.h
@@ -32,10 +32,15 @@
   // Attempts to acquire an exclusive file lock (see flock(2)) on the file
   // at filename, and blocks until it can do so.
   //
-  // Returns true if the lock could be acquired, or false if an error
-  // occurred. It is an error if the file does not exist, or if its inode
-  // changed (usually due to a new file being created at the same path)
-  // between attempts to lock it.
+  // Returns true if the lock could be acquired, or false if an error occurred.
+  // It is an error if its inode changed (usually due to a new file being
+  // created at the same path) between attempts to lock it. In blocking mode,
+  // locking will be retried if the file changed. In non-blocking mode, false
+  // is returned and no attempt is made to re-acquire the lock.
+  //
+  // The file is opened with the provided flags.
+  bool Init(const char* filename, int flags, bool block, std::string* error_msg);
+  // Calls Init(filename, O_CREAT | O_RDWR, true, errror_msg)
   bool Init(const char* filename, std::string* error_msg);
   // Attempt to acquire an exclusive file lock (see flock(2)) on 'file'.
   // Returns true if the lock could be acquired or false if an error
@@ -43,7 +48,7 @@
   bool Init(File* file, std::string* error_msg);
 
   // Returns the (locked) file associated with this instance.
-  File* GetFile();
+  File* GetFile() const;
 
   // Returns whether a file is held.
   bool HasFile();
diff --git a/runtime/base/unix_file/fd_file.cc b/runtime/base/unix_file/fd_file.cc
index 78bc3d5..e17bebb 100644
--- a/runtime/base/unix_file/fd_file.cc
+++ b/runtime/base/unix_file/fd_file.cc
@@ -316,4 +316,21 @@
   guard_state_ = GuardState::kNoCheck;
 }
 
+bool FdFile::ClearContent() {
+  if (SetLength(0) < 0) {
+    PLOG(art::ERROR) << "Failed to reset the length";
+    return false;
+  }
+  return ResetOffset();
+}
+
+bool FdFile::ResetOffset() {
+  off_t rc =  TEMP_FAILURE_RETRY(lseek(fd_, 0, SEEK_SET));
+  if (rc == static_cast<off_t>(-1)) {
+    PLOG(art::ERROR) << "Failed to reset the offset";
+    return false;
+  }
+  return true;
+}
+
 }  // namespace unix_file
diff --git a/runtime/base/unix_file/fd_file.h b/runtime/base/unix_file/fd_file.h
index 231a1ab..1e2d8af 100644
--- a/runtime/base/unix_file/fd_file.h
+++ b/runtime/base/unix_file/fd_file.h
@@ -79,6 +79,11 @@
 
   // Copy data from another file.
   bool Copy(FdFile* input_file, int64_t offset, int64_t size);
+  // Clears the file content and resets the file offset to 0.
+  // Returns true upon success, false otherwise.
+  bool ClearContent();
+  // Resets the file offset to the beginning of the file.
+  bool ResetOffset();
 
   // This enum is public so that we can define the << operator over it.
   enum class GuardState {
diff --git a/runtime/jit/offline_profiling_info.cc b/runtime/jit/offline_profiling_info.cc
index a132701..b4b872f 100644
--- a/runtime/jit/offline_profiling_info.cc
+++ b/runtime/jit/offline_profiling_info.cc
@@ -24,8 +24,11 @@
 
 #include "art_method-inl.h"
 #include "base/mutex.h"
+#include "base/scoped_flock.h"
 #include "base/stl_util.h"
+#include "base/unix_file/fd_file.h"
 #include "jit/profiling_info.h"
+#include "os.h"
 #include "safe_map.h"
 
 namespace art {
@@ -37,8 +40,17 @@
     return true;
   }
 
+  ScopedFlock flock;
+  std::string error;
+  if (!flock.Init(filename.c_str(), O_RDWR | O_NOFOLLOW | O_CLOEXEC, /* block */ false, &error)) {
+    LOG(WARNING) << "Couldn't lock the profile file " << filename << ": " << error;
+    return false;
+  }
+
+  int fd = flock.GetFile()->Fd();
+
   ProfileCompilationInfo info;
-  if (!info.Load(filename)) {
+  if (!info.Load(fd)) {
     LOG(WARNING) << "Could not load previous profile data from file " << filename;
     return false;
   }
@@ -54,9 +66,14 @@
     }
   }
 
+  if (!flock.GetFile()->ClearContent()) {
+    PLOG(WARNING) << "Could not clear profile file: " << filename;
+    return false;
+  }
+
   // This doesn't need locking because we are trying to lock the file for exclusive
   // access and fail immediately if we can't.
-  bool result = info.Save(filename);
+  bool result = info.Save(fd);
   if (result) {
     VLOG(profiler) << "Successfully saved profile info to " << filename
         << " Size: " << GetFileSizeBytes(filename);
@@ -66,64 +83,20 @@
   return result;
 }
 
-enum OpenMode {
-  READ,
-  READ_WRITE
-};
-
-static int OpenFile(const std::string& filename, OpenMode open_mode) {
-  int fd = -1;
-  switch (open_mode) {
-    case READ:
-      fd = open(filename.c_str(), O_RDONLY);
-      break;
-    case READ_WRITE:
-      // TODO(calin) allow the shared uid of the app to access the file.
-      fd = open(filename.c_str(), O_WRONLY | O_TRUNC | O_NOFOLLOW | O_CLOEXEC);
-      break;
-  }
-
-  if (fd < 0) {
-    PLOG(WARNING) << "Failed to open profile file " << filename;
-    return -1;
-  }
-
-  // Lock the file for exclusive access but don't wait if we can't lock it.
-  int err = flock(fd, LOCK_EX | LOCK_NB);
-  if (err < 0) {
-    PLOG(WARNING) << "Failed to lock profile file " << filename;
-    return -1;
-  }
-  return fd;
-}
-
-static bool CloseDescriptorForFile(int fd, const std::string& filename) {
-  // Now unlock the file, allowing another process in.
-  int err = flock(fd, LOCK_UN);
-  if (err < 0) {
-    PLOG(WARNING) << "Failed to unlock profile file " << filename;
-    return false;
-  }
-
-  // Done, close the file.
-  err = ::close(fd);
-  if (err < 0) {
-    PLOG(WARNING) << "Failed to close descriptor for profile file" << filename;
-    return false;
-  }
-
-  return true;
-}
-
-static void WriteToFile(int fd, const std::ostringstream& os) {
+static bool WriteToFile(int fd, const std::ostringstream& os) {
   std::string data(os.str());
   const char *p = data.c_str();
   size_t length = data.length();
   do {
-    int n = ::write(fd, p, length);
+    int n = TEMP_FAILURE_RETRY(write(fd, p, length));
+    if (n < 0) {
+      PLOG(WARNING) << "Failed to write to descriptor: " << fd;
+      return false;
+    }
     p += n;
     length -= n;
   } while (length > 0);
+  return true;
 }
 
 static constexpr const char kFieldSeparator = ',';
@@ -137,13 +110,8 @@
  *    /system/priv-app/app/app.apk,131232145,11,23,454,54
  *    /system/priv-app/app/app.apk:classes5.dex,218490184,39,13,49,1
  **/
-bool ProfileCompilationInfo::Save(const std::string& filename) {
-  int fd = OpenFile(filename, READ_WRITE);
-  if (fd == -1) {
-    return false;
-  }
-
-  // TODO(calin): Merge with a previous existing profile.
+bool ProfileCompilationInfo::Save(uint32_t fd) {
+  DCHECK_GE(fd, 0u);
   // TODO(calin): Profile this and see how much memory it takes. If too much,
   // write to file directly.
   std::ostringstream os;
@@ -158,9 +126,7 @@
     os << kLineSeparator;
   }
 
-  WriteToFile(fd, os);
-
-  return CloseDescriptorForFile(fd, filename);
+  return WriteToFile(fd, os);
 }
 
 // TODO(calin): This a duplicate of Utils::Split fixing the case where the first character
@@ -222,7 +188,9 @@
       LOG(WARNING) << "Cannot parse method_idx " << parts[i];
       return false;
     }
-    AddData(dex_location, checksum, method_idx);
+    if (!AddData(dex_location, checksum, method_idx)) {
+      return false;
+    }
   }
   return true;
 }
@@ -249,23 +217,18 @@
   return new_line_pos == -1 ? new_line_pos : new_line_pos + 1;
 }
 
-bool ProfileCompilationInfo::Load(const std::string& filename) {
-  int fd = OpenFile(filename, READ);
-  if (fd == -1) {
-    return false;
-  }
+bool ProfileCompilationInfo::Load(uint32_t fd) {
+  DCHECK_GE(fd, 0u);
 
   std::string current_line;
   const int kBufferSize = 1024;
   char buffer[kBufferSize];
-  bool success = true;
 
-  while (success) {
-    int n = read(fd, buffer, kBufferSize);
+  while (true) {
+    int n = TEMP_FAILURE_RETRY(read(fd, buffer, kBufferSize));
     if (n < 0) {
-      PLOG(WARNING) << "Error when reading profile file " << filename;
-      success = false;
-      break;
+      PLOG(WARNING) << "Error when reading profile file";
+      return false;
     } else if (n == 0) {
       break;
     }
@@ -278,17 +241,13 @@
         break;
       }
       if (!ProcessLine(current_line)) {
-        success = false;
-        break;
+        return false;
       }
       // Reset the current line (we just processed it).
       current_line.clear();
     }
   }
-  if (!success) {
-    info_.clear();
-  }
-  return CloseDescriptorForFile(fd, filename) && success;
+  return true;
 }
 
 bool ProfileCompilationInfo::Load(const ProfileCompilationInfo& other) {
@@ -369,4 +328,8 @@
   return os.str();
 }
 
+bool ProfileCompilationInfo::Equals(ProfileCompilationInfo& other) {
+  return info_.Equals(other.info_);
+}
+
 }  // namespace art
diff --git a/runtime/jit/offline_profiling_info.h b/runtime/jit/offline_profiling_info.h
index 26e1ac3..ffd1433 100644
--- a/runtime/jit/offline_profiling_info.h
+++ b/runtime/jit/offline_profiling_info.h
@@ -39,15 +39,18 @@
  */
 class ProfileCompilationInfo {
  public:
+  // Saves profile information about the given methods in the given file.
+  // Note that the saving proceeds only if the file can be locked for exclusive access.
+  // If not (the locking is not blocking), the function does not save and returns false.
   static bool SaveProfilingInfo(const std::string& filename,
                                 const std::vector<ArtMethod*>& methods);
 
-  // Loads profile information from the given file.
-  bool Load(const std::string& profile_filename);
+  // Loads profile information from the given file descriptor.
+  bool Load(uint32_t fd);
   // Loads the data from another ProfileCompilationInfo object.
   bool Load(const ProfileCompilationInfo& info);
-  // Saves the profile data to the given file.
-  bool Save(const std::string& profile_filename);
+  // Saves the profile data to the given file descriptor.
+  bool Save(uint32_t fd);
   // Returns the number of methods that were profiled.
   uint32_t GetNumberOfMethods() const;
 
@@ -61,6 +64,9 @@
   std::string DumpInfo(const std::vector<const DexFile*>* dex_files,
                        bool print_full_dex_location = true) const;
 
+  // For testing purposes.
+  bool Equals(ProfileCompilationInfo& other);
+
  private:
   bool AddData(const std::string& dex_location, uint32_t checksum, uint16_t method_idx);
   bool ProcessLine(const std::string& line);
@@ -69,10 +75,18 @@
     explicit DexFileData(uint32_t location_checksum) : checksum(location_checksum) {}
     uint32_t checksum;
     std::set<uint16_t> method_set;
+
+    bool operator==(const DexFileData& other) const {
+      return checksum == other.checksum && method_set == other.method_set;
+    }
   };
 
   using DexFileToProfileInfoMap = SafeMap<const std::string, DexFileData>;
 
+  friend class ProfileCompilationInfoTest;
+  friend class CompilerDriverProfileTest;
+  friend class ProfileAssistantTest;
+
   DexFileToProfileInfoMap info_;
 };
 
diff --git a/runtime/jit/profile_compilation_info_test.cc b/runtime/jit/profile_compilation_info_test.cc
new file mode 100644
index 0000000..482ea06
--- /dev/null
+++ b/runtime/jit/profile_compilation_info_test.cc
@@ -0,0 +1,166 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <gtest/gtest.h>
+
+#include "base/unix_file/fd_file.h"
+#include "art_method-inl.h"
+#include "class_linker-inl.h"
+#include "common_runtime_test.h"
+#include "dex_file.h"
+#include "mirror/class-inl.h"
+#include "mirror/class_loader.h"
+#include "handle_scope-inl.h"
+#include "jit/offline_profiling_info.h"
+#include "scoped_thread_state_change.h"
+
+namespace art {
+
+class ProfileCompilationInfoTest : public CommonRuntimeTest {
+ protected:
+  std::vector<ArtMethod*> GetVirtualMethods(jobject class_loader,
+                                            const std::string& clazz) {
+    ClassLinker* class_linker = Runtime::Current()->GetClassLinker();
+    Thread* self = Thread::Current();
+    ScopedObjectAccess soa(self);
+    StackHandleScope<1> hs(self);
+    Handle<mirror::ClassLoader> h_loader(hs.NewHandle(
+        reinterpret_cast<mirror::ClassLoader*>(self->DecodeJObject(class_loader))));
+    mirror::Class* klass = class_linker->FindClass(self, clazz.c_str(), h_loader);
+
+    const auto pointer_size = class_linker->GetImagePointerSize();
+    std::vector<ArtMethod*> methods;
+    for (auto& m : klass->GetVirtualMethods(pointer_size)) {
+      methods.push_back(&m);
+    }
+    return methods;
+  }
+
+  bool AddData(const std::string& dex_location,
+               uint32_t checksum,
+               uint16_t method_index,
+               ProfileCompilationInfo* info) {
+    return info->AddData(dex_location, checksum, method_index);
+  }
+
+  uint32_t GetFd(const ScratchFile& file) {
+    return static_cast<uint32_t>(file.GetFd());
+  }
+};
+
+TEST_F(ProfileCompilationInfoTest, SaveArtMethods) {
+  ScratchFile profile;
+
+  Thread* self = Thread::Current();
+  jobject class_loader;
+  {
+    ScopedObjectAccess soa(self);
+    class_loader = LoadDex("ProfileTestMultiDex");
+  }
+  ASSERT_NE(class_loader, nullptr);
+
+  // Save virtual methods from Main.
+  std::vector<ArtMethod*> main_methods = GetVirtualMethods(class_loader, "LMain;");
+  ASSERT_TRUE(ProfileCompilationInfo::SaveProfilingInfo(profile.GetFilename(), main_methods));
+
+  // Check that what we saved is in the profile.
+  ProfileCompilationInfo info1;
+  ASSERT_TRUE(info1.Load(GetFd(profile)));
+  ASSERT_EQ(info1.GetNumberOfMethods(), main_methods.size());
+  {
+    ScopedObjectAccess soa(self);
+    for (ArtMethod* m : main_methods) {
+      ASSERT_TRUE(info1.ContainsMethod(MethodReference(m->GetDexFile(), m->GetDexMethodIndex())));
+    }
+  }
+
+  // Save virtual methods from Second.
+  std::vector<ArtMethod*> second_methods = GetVirtualMethods(class_loader, "LSecond;");
+  ASSERT_TRUE(ProfileCompilationInfo::SaveProfilingInfo(profile.GetFilename(), second_methods));
+
+  // Check that what we saved is in the profile (methods form Main and Second).
+  ProfileCompilationInfo info2;
+  ASSERT_TRUE(profile.GetFile()->ResetOffset());
+  ASSERT_TRUE(info2.Load(GetFd(profile)));
+  ASSERT_EQ(info2.GetNumberOfMethods(), main_methods.size() + second_methods.size());
+  {
+    ScopedObjectAccess soa(self);
+    for (ArtMethod* m : main_methods) {
+      ASSERT_TRUE(info2.ContainsMethod(MethodReference(m->GetDexFile(), m->GetDexMethodIndex())));
+    }
+    for (ArtMethod* m : second_methods) {
+      ASSERT_TRUE(info2.ContainsMethod(MethodReference(m->GetDexFile(), m->GetDexMethodIndex())));
+    }
+  }
+}
+
+TEST_F(ProfileCompilationInfoTest, SaveFd) {
+  ScratchFile profile;
+
+  ProfileCompilationInfo saved_info;
+  // Save a few methods.
+  for (uint16_t i = 0; i < 10; i++) {
+    ASSERT_TRUE(AddData("dex_location1", /* checksum */ 1, /* method_idx */ i, &saved_info));
+    ASSERT_TRUE(AddData("dex_location2", /* checksum */ 2, /* method_idx */ i, &saved_info));
+  }
+  ASSERT_TRUE(saved_info.Save(GetFd(profile)));
+  ASSERT_EQ(0, profile.GetFile()->Flush());
+
+  // Check that we get back what we saved.
+  ProfileCompilationInfo loaded_info;
+  ASSERT_TRUE(profile.GetFile()->ResetOffset());
+  ASSERT_TRUE(loaded_info.Load(GetFd(profile)));
+  ASSERT_TRUE(loaded_info.Equals(saved_info));
+
+  // Save more methods.
+  for (uint16_t i = 0; i < 100; i++) {
+    ASSERT_TRUE(AddData("dex_location1", /* checksum */ 1, /* method_idx */ i, &saved_info));
+    ASSERT_TRUE(AddData("dex_location2", /* checksum */ 2, /* method_idx */ i, &saved_info));
+    ASSERT_TRUE(AddData("dex_location3", /* checksum */ 3, /* method_idx */ i, &saved_info));
+  }
+  ASSERT_TRUE(profile.GetFile()->ResetOffset());
+  ASSERT_TRUE(saved_info.Save(GetFd(profile)));
+  ASSERT_EQ(0, profile.GetFile()->Flush());
+
+  // Check that we get back everything we saved.
+  ProfileCompilationInfo loaded_info2;
+  ASSERT_TRUE(profile.GetFile()->ResetOffset());
+  ASSERT_TRUE(loaded_info2.Load(GetFd(profile)));
+  ASSERT_TRUE(loaded_info2.Equals(saved_info));
+}
+
+TEST_F(ProfileCompilationInfoTest, AddDataFail) {
+  ScratchFile profile;
+
+  ProfileCompilationInfo info;
+  ASSERT_TRUE(AddData("dex_location", /* checksum */ 1, /* method_idx */ 1, &info));
+  // Trying to add info for an existing file but with a different checksum.
+  ASSERT_FALSE(AddData("dex_location", /* checksum */ 2, /* method_idx */ 2, &info));
+}
+
+TEST_F(ProfileCompilationInfoTest, LoadFail) {
+  ScratchFile profile;
+
+  ProfileCompilationInfo info1;
+  ASSERT_TRUE(AddData("dex_location", /* checksum */ 1, /* method_idx */ 1, &info1));
+  // Use the same file, change the checksum.
+  ProfileCompilationInfo info2;
+  ASSERT_TRUE(AddData("dex_location", /* checksum */ 2, /* method_idx */ 2, &info2));
+
+  ASSERT_FALSE(info1.Load(info2));
+}
+
+}  // namespace art
diff --git a/runtime/jit/profile_saver.cc b/runtime/jit/profile_saver.cc
index ec289ea..fc257c0 100644
--- a/runtime/jit/profile_saver.cc
+++ b/runtime/jit/profile_saver.cc
@@ -86,12 +86,14 @@
 }
 
 bool ProfileSaver::ProcessProfilingInfo() {
-  VLOG(profiler) << "Initiating save profiling information to: " << output_filename_;
+  VLOG(profiler) << "Save profiling information to: " << output_filename_;
 
   uint64_t last_update_time_ns = jit_code_cache_->GetLastUpdateTimeNs();
   if (last_update_time_ns - code_cache_last_update_time_ns_
-      > kMinimumTimeBetweenCodeCacheUpdatesNs) {
-    VLOG(profiler) << "Not enough time has passed since the last code cache update.";
+      < kMinimumTimeBetweenCodeCacheUpdatesNs) {
+    VLOG(profiler) << "Not enough time has passed since the last code cache update."
+        << "Last update: " << last_update_time_ns
+        << " Last save: " << code_cache_last_update_time_ns_;
     return false;
   }