Merge changes I6791dd72,I887d5073

* changes:
  Reduce priority of merge threads
  Tune snapshot-merge performance
diff --git a/debuggerd/Android.bp b/debuggerd/Android.bp
index 5c7d847..ad0231d 100644
--- a/debuggerd/Android.bp
+++ b/debuggerd/Android.bp
@@ -293,13 +293,6 @@
         "libdebuggerd/test/utility_test.cpp",
     ],
 
-    product_variables: {
-        malloc_not_svelte: {
-            srcs: ["libdebuggerd/test/scudo_test.cpp"],
-            header_libs: ["scudo_headers"],
-        },
-    },
-
     target: {
         android: {
             srcs: [
diff --git a/debuggerd/libdebuggerd/include/libdebuggerd/scudo.h b/debuggerd/libdebuggerd/include/libdebuggerd/scudo.h
index 68bfd5b..a506859 100644
--- a/debuggerd/libdebuggerd/include/libdebuggerd/scudo.h
+++ b/debuggerd/libdebuggerd/include/libdebuggerd/scudo.h
@@ -34,10 +34,9 @@
 
 class ScudoCrashData {
  public:
-  ScudoCrashData() = default;
+  ScudoCrashData() = delete;
   ~ScudoCrashData() = default;
-
-  bool SetErrorInfo(unwindstack::Memory* process_memory, const ProcessInfo& process_info);
+  ScudoCrashData(unwindstack::Memory* process_memory, const ProcessInfo& process_info);
 
   bool CrashIsMine() const;
 
diff --git a/debuggerd/libdebuggerd/scudo.cpp b/debuggerd/libdebuggerd/scudo.cpp
index 9483e59..5d861f8 100644
--- a/debuggerd/libdebuggerd/scudo.cpp
+++ b/debuggerd/libdebuggerd/scudo.cpp
@@ -14,11 +14,6 @@
  * limitations under the License.
  */
 
-#include <stdint.h>
-#include <unistd.h>
-
-#include <vector>
-
 #include "libdebuggerd/scudo.h"
 #include "libdebuggerd/tombstone.h"
 
@@ -30,92 +25,57 @@
 
 #include "tombstone.pb.h"
 
-bool ScudoCrashData::SetErrorInfo(unwindstack::Memory* process_memory,
-                                  const ProcessInfo& process_info) {
+std::unique_ptr<char[]> AllocAndReadFully(unwindstack::Memory* process_memory, uint64_t addr,
+                                          size_t size) {
+  auto buf = std::make_unique<char[]>(size);
+  if (!process_memory->ReadFully(addr, buf.get(), size)) {
+    return std::unique_ptr<char[]>();
+  }
+  return buf;
+}
+
+ScudoCrashData::ScudoCrashData(unwindstack::Memory* process_memory,
+                               const ProcessInfo& process_info) {
   if (!process_info.has_fault_address) {
-    return false;
+    return;
   }
 
-  std::vector<char> stack_depot(__scudo_get_stack_depot_size());
-  if (!process_memory->ReadFully(process_info.scudo_stack_depot, stack_depot.data(),
-                                 stack_depot.size())) {
-    return false;
+  auto stack_depot = AllocAndReadFully(process_memory, process_info.scudo_stack_depot,
+                                       __scudo_get_stack_depot_size());
+  auto region_info = AllocAndReadFully(process_memory, process_info.scudo_region_info,
+                                       __scudo_get_region_info_size());
+  auto ring_buffer = AllocAndReadFully(process_memory, process_info.scudo_ring_buffer,
+                                       __scudo_get_ring_buffer_size());
+  if (!stack_depot || !region_info || !ring_buffer) {
+    return;
   }
-  std::vector<char> region_info(__scudo_get_region_info_size());
-  if (!process_memory->ReadFully(process_info.scudo_region_info, region_info.data(),
-                                 region_info.size())) {
-    return false;
-  }
-  std::vector<char> ring_buffer(__scudo_get_ring_buffer_size());
-  if (!process_memory->ReadFully(process_info.scudo_ring_buffer, ring_buffer.data(),
-                                 ring_buffer.size())) {
-    return false;
-  }
-
-  uintptr_t page_size = getpagesize();
 
   untagged_fault_addr_ = process_info.untagged_fault_address;
-  uintptr_t fault_page = untagged_fault_addr_ & ~(page_size - 1);
+  uintptr_t fault_page = untagged_fault_addr_ & ~(PAGE_SIZE - 1);
 
-  // Attempt to get 16 pages before the fault page and 16 pages after.
-  constexpr size_t kExtraPages = 16;
-  std::vector<char> memory(page_size * (kExtraPages * 2 + 1));
-
-  // Read faulting page first.
-  size_t memory_index = kExtraPages;
-  if (!process_memory->ReadFully(fault_page, &memory[memory_index * page_size], page_size)) {
-    return false;
+  uintptr_t memory_begin = fault_page - PAGE_SIZE * 16;
+  if (memory_begin > fault_page) {
+    return;
   }
 
-  // Attempt to read the pages after the fault page, stop as soon as we
-  // fail to read.
-  uintptr_t read_addr = fault_page;
-  if (!__builtin_add_overflow(fault_page, page_size, &read_addr)) {
-    memory_index++;
-    for (size_t i = 0; i < kExtraPages; i++, memory_index++) {
-      if (!process_memory->ReadFully(read_addr, &memory[memory_index * page_size], page_size)) {
-        break;
-      }
-      if (__builtin_add_overflow(read_addr, page_size, &read_addr)) {
-        break;
-      }
-    }
-  }
-  uintptr_t memory_end = read_addr;
-
-  // Attempt to read the pages before the fault page, stop as soon as we
-  // fail to read.
-  memory_index = kExtraPages;
-  if (fault_page > 0) {
-    read_addr = fault_page - page_size;
-    for (size_t i = 0; i < kExtraPages; i++, memory_index--) {
-      if (!process_memory->ReadFully(read_addr, &memory[(memory_index - 1) * page_size],
-                                     page_size)) {
-        break;
-      }
-      if (read_addr == 0) {
-        memory_index--;
-        break;
-      }
-      read_addr -= page_size;
-    }
-  }
-  size_t start_memory_index = memory_index;
-  uintptr_t memory_begin = fault_page - (kExtraPages - memory_index) * page_size;
-
-  std::vector<long> memory_tags((memory_end - memory_begin) / kTagGranuleSize);
-  read_addr = memory_begin;
-  for (size_t i = 0; i < memory_tags.size(); i++) {
-    memory_tags[i] = process_memory->ReadTag(read_addr);
-    read_addr += kTagGranuleSize;
+  uintptr_t memory_end = fault_page + PAGE_SIZE * 16;
+  if (memory_end < fault_page) {
+    return;
   }
 
-  __scudo_get_error_info(
-      &error_info_, process_info.maybe_tagged_fault_address, stack_depot.data(), region_info.data(),
-      ring_buffer.data(), &memory[start_memory_index * page_size],
-      reinterpret_cast<const char*>(memory_tags.data()), memory_begin, memory_end - memory_begin);
+  auto memory = std::make_unique<char[]>(memory_end - memory_begin);
+  for (auto i = memory_begin; i != memory_end; i += PAGE_SIZE) {
+    process_memory->ReadFully(i, memory.get() + i - memory_begin, PAGE_SIZE);
+  }
 
-  return true;
+  auto memory_tags = std::make_unique<char[]>((memory_end - memory_begin) / kTagGranuleSize);
+  for (auto i = memory_begin; i != memory_end; i += kTagGranuleSize) {
+    memory_tags[(i - memory_begin) / kTagGranuleSize] = process_memory->ReadTag(i);
+  }
+
+  __scudo_get_error_info(&error_info_, process_info.maybe_tagged_fault_address, stack_depot.get(),
+                         region_info.get(), ring_buffer.get(), memory.get(), memory_tags.get(),
+                         memory_begin, memory_end - memory_begin);
 }
 
 bool ScudoCrashData::CrashIsMine() const {
diff --git a/debuggerd/libdebuggerd/test/scudo_test.cpp b/debuggerd/libdebuggerd/test/scudo_test.cpp
deleted file mode 100644
index d8fc6a7..0000000
--- a/debuggerd/libdebuggerd/test/scudo_test.cpp
+++ /dev/null
@@ -1,233 +0,0 @@
-/*
- * Copyright (C) 2022 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 <stdlib.h>
-#include <unistd.h>
-
-#include <gmock/gmock.h>
-#include <gtest/gtest.h>
-
-#include "libdebuggerd/scudo.h"
-#include "libdebuggerd/types.h"
-#include "unwindstack/Memory.h"
-
-#include "log_fake.h"
-
-#include <inttypes.h>
-
-// This needs to match the kExtraPages from ScudoCrashData::SetErrorInfo.
-constexpr uint64_t kMaxPages = 16;
-
-class MemoryAlwaysZero : public unwindstack::Memory {
- public:
-  MemoryAlwaysZero() = default;
-  virtual ~MemoryAlwaysZero() = default;
-
-  size_t Read(uint64_t addr, void* buffer, size_t size) override {
-    if (test_unreadable_addrs_.count(addr) != 0) {
-      return 0;
-    }
-    test_read_addrs_.insert(addr);
-    memset(buffer, 0, size);
-    return size;
-  }
-
-  void TestAddUnreadableAddress(uint64_t addr) { test_unreadable_addrs_.insert(addr); }
-
-  void TestClearAddresses() {
-    test_read_addrs_.clear();
-    test_unreadable_addrs_.clear();
-  }
-
-  std::set<uint64_t>& test_read_addrs() { return test_read_addrs_; }
-
- private:
-  std::set<uint64_t> test_unreadable_addrs_;
-
-  std::set<uint64_t> test_read_addrs_;
-};
-
-TEST(ScudoTest, no_fault_address) {
-  MemoryAlwaysZero process_memory;
-  ProcessInfo info;
-  info.has_fault_address = false;
-  info.untagged_fault_address = 0x5000;
-  info.scudo_stack_depot = 0x1000;
-  info.scudo_region_info = 0x2000;
-  info.scudo_ring_buffer = 0x3000;
-
-  ScudoCrashData crash;
-  ASSERT_FALSE(crash.SetErrorInfo(&process_memory, info));
-
-  info.has_fault_address = true;
-  ASSERT_TRUE(crash.SetErrorInfo(&process_memory, info));
-}
-
-TEST(ScudoTest, scudo_data_read_check) {
-  MemoryAlwaysZero process_memory;
-  ProcessInfo info;
-  info.has_fault_address = true;
-  info.untagged_fault_address = 0x5000;
-  info.scudo_stack_depot = 0x1000;
-  info.scudo_region_info = 0x2000;
-  info.scudo_ring_buffer = 0x3000;
-
-  ScudoCrashData crash;
-  ASSERT_TRUE(crash.SetErrorInfo(&process_memory, info));
-
-  // Stack Depot unreadable
-  process_memory.TestClearAddresses();
-  process_memory.TestAddUnreadableAddress(0x1000);
-  ASSERT_FALSE(crash.SetErrorInfo(&process_memory, info));
-
-  // The Region Info doesn't exist for 32 bit.
-#if defined(__LP64__)
-  // Region Info unreadable
-  process_memory.TestClearAddresses();
-  process_memory.TestAddUnreadableAddress(0x2000);
-  ASSERT_FALSE(crash.SetErrorInfo(&process_memory, info));
-#endif
-
-  // Ring Buffer unreadable
-  process_memory.TestClearAddresses();
-  process_memory.TestAddUnreadableAddress(0x3000);
-  ASSERT_FALSE(crash.SetErrorInfo(&process_memory, info));
-
-  // Verify that with all scudo data readable, the error info works.
-  process_memory.TestClearAddresses();
-  ASSERT_TRUE(crash.SetErrorInfo(&process_memory, info));
-}
-
-TEST(ScudoTest, fault_page_unreadable) {
-  MemoryAlwaysZero process_memory;
-  ProcessInfo info;
-  info.has_fault_address = true;
-  info.untagged_fault_address = 0x5124;
-  info.scudo_stack_depot = 0x1000;
-  info.scudo_region_info = 0x2000;
-  info.scudo_ring_buffer = 0x3000;
-
-  ScudoCrashData crash;
-  ASSERT_TRUE(crash.SetErrorInfo(&process_memory, info));
-
-  uint64_t fault_page = info.untagged_fault_address & ~(getpagesize() - 1);
-  process_memory.TestAddUnreadableAddress(fault_page);
-  ASSERT_FALSE(crash.SetErrorInfo(&process_memory, info));
-}
-
-TEST(ScudoTest, pages_before_fault_unreadable) {
-  MemoryAlwaysZero process_memory;
-  ProcessInfo info;
-  info.has_fault_address = true;
-  info.untagged_fault_address = 0x15124;
-  info.scudo_stack_depot = 0x1000;
-  info.scudo_region_info = 0x2000;
-  info.scudo_ring_buffer = 0x3000;
-
-  ScudoCrashData crash;
-  ASSERT_TRUE(crash.SetErrorInfo(&process_memory, info));
-
-  uint64_t page_size = getpagesize();
-  uint64_t fault_page = info.untagged_fault_address & ~(page_size - 1);
-
-  std::vector<uint64_t> expected_reads = {0x1000, 0x2000, 0x3000};
-  for (size_t i = 0; i <= kMaxPages; i++) {
-    expected_reads.emplace_back(fault_page + i * page_size);
-  }
-
-  // Loop through and make pages before the fault page unreadable.
-  for (size_t i = 1; i <= kMaxPages + 1; i++) {
-    process_memory.TestClearAddresses();
-    uint64_t unreadable_addr = fault_page - i * page_size;
-    SCOPED_TRACE(testing::Message()
-                 << "Failed at unreadable address 0x" << std::hex << unreadable_addr);
-    process_memory.TestAddUnreadableAddress(unreadable_addr);
-    ASSERT_TRUE(crash.SetErrorInfo(&process_memory, info));
-    ASSERT_THAT(process_memory.test_read_addrs(),
-                testing::UnorderedElementsAreArray(expected_reads));
-    // Need to add the previous unreadable_addr to the list of expected addresses.
-    expected_reads.emplace_back(unreadable_addr);
-  }
-}
-
-TEST(ScudoTest, pages_after_fault_unreadable) {
-  MemoryAlwaysZero process_memory;
-  ProcessInfo info;
-  info.has_fault_address = true;
-  info.untagged_fault_address = 0x15124;
-  info.scudo_stack_depot = 0x1000;
-  info.scudo_region_info = 0x2000;
-  info.scudo_ring_buffer = 0x3000;
-
-  ScudoCrashData crash;
-  ASSERT_TRUE(crash.SetErrorInfo(&process_memory, info));
-
-  uint64_t page_size = getpagesize();
-  uint64_t fault_page = info.untagged_fault_address & ~(page_size - 1);
-
-  std::vector<uint64_t> expected_reads = {0x1000, 0x2000, 0x3000};
-  for (size_t i = 0; i <= kMaxPages; i++) {
-    expected_reads.emplace_back(fault_page - i * page_size);
-  }
-
-  // Loop through and make pages after the fault page unreadable.
-  for (size_t i = 1; i <= kMaxPages + 1; i++) {
-    process_memory.TestClearAddresses();
-    uint64_t unreadable_addr = fault_page + i * page_size;
-    SCOPED_TRACE(testing::Message()
-                 << "Failed at unreadable address 0x" << std::hex << unreadable_addr);
-    process_memory.TestAddUnreadableAddress(unreadable_addr);
-    ASSERT_TRUE(crash.SetErrorInfo(&process_memory, info));
-    ASSERT_THAT(process_memory.test_read_addrs(),
-                testing::UnorderedElementsAreArray(expected_reads));
-    // Need to add the previous unreadable_addr to the list of expected addresses.
-    expected_reads.emplace_back(unreadable_addr);
-  }
-}
-
-// Make sure that if the fault address is low, you won't underflow.
-TEST(ScudoTest, fault_address_low) {
-  MemoryAlwaysZero process_memory;
-  ProcessInfo info;
-  info.has_fault_address = true;
-  info.scudo_stack_depot = 0x21000;
-  info.scudo_region_info = 0x22000;
-  info.scudo_ring_buffer = 0x23000;
-
-  ScudoCrashData crash;
-  ASSERT_TRUE(crash.SetErrorInfo(&process_memory, info));
-
-  uint64_t page_size = getpagesize();
-  for (size_t i = 0; i < kMaxPages + 1; i++) {
-    process_memory.TestClearAddresses();
-    info.untagged_fault_address = 0x124 + i * getpagesize();
-    SCOPED_TRACE(testing::Message()
-                 << "Failed with fault address 0x" << std::hex << info.untagged_fault_address);
-    ASSERT_TRUE(crash.SetErrorInfo(&process_memory, info));
-    std::vector<uint64_t> expected_reads = {0x21000, 0x22000, 0x23000};
-    uint64_t fault_page = info.untagged_fault_address & ~(page_size - 1);
-    expected_reads.emplace_back(fault_page);
-    for (size_t j = 1; j <= kMaxPages; j++) {
-      expected_reads.emplace_back(fault_page + j * page_size);
-    }
-    while (fault_page != 0) {
-      fault_page -= page_size;
-      expected_reads.emplace_back(fault_page);
-    }
-    ASSERT_THAT(process_memory.test_read_addrs(),
-                testing::UnorderedElementsAreArray(expected_reads));
-  }
-}
diff --git a/debuggerd/libdebuggerd/tombstone_proto.cpp b/debuggerd/libdebuggerd/tombstone_proto.cpp
index 6e1ce8f..159ebc8 100644
--- a/debuggerd/libdebuggerd/tombstone_proto.cpp
+++ b/debuggerd/libdebuggerd/tombstone_proto.cpp
@@ -193,9 +193,8 @@
 static void dump_probable_cause(Tombstone* tombstone, unwindstack::AndroidUnwinder* unwinder,
                                 const ProcessInfo& process_info, const ThreadInfo& main_thread) {
 #if defined(USE_SCUDO)
-  ScudoCrashData scudo_crash_data;
-  if (scudo_crash_data.SetErrorInfo(unwinder->GetProcessMemory().get(), process_info) &&
-      scudo_crash_data.CrashIsMine()) {
+  ScudoCrashData scudo_crash_data(unwinder->GetProcessMemory().get(), process_info);
+  if (scudo_crash_data.CrashIsMine()) {
     scudo_crash_data.AddCauseProtos(tombstone, unwinder);
     return;
   }