runtime/indirect_reference_table.cc - platform/art - Gitiles

 /*
  * Copyright (C) 2009 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 "indirect_reference_table-inl.h"

 #include "base/dumpable-inl.h"
 #include "base/systrace.h"
 #include "jni_internal.h"
 #include "nth_caller_visitor.h"
 #include "reference_table.h"
 #include "runtime.h"
 #include "scoped_thread_state_change-inl.h"
 #include "thread.h"
 #include "utils.h"
 #include "verify_object-inl.h"

 #include <cstdlib>

 namespace art {

 static constexpr bool kDumpStackOnNonLocalReference = false;

 const char* GetIndirectRefKindString(const IndirectRefKind& kind) {
   switch (kind) {
     case kHandleScopeOrInvalid:
       return "HandleScopeOrInvalid";
     case kLocal:
       return "Local";
     case kGlobal:
       return "Global";
     case kWeakGlobal:
       return "WeakGlobal";
   }
   return "IndirectRefKind Error";
 }

 void IndirectReferenceTable::AbortIfNoCheckJNI(const std::string& msg) {
   // If -Xcheck:jni is on, it'll give a more detailed error before aborting.
   JavaVMExt* vm = Runtime::Current()->GetJavaVM();
   if (!vm->IsCheckJniEnabled()) {
     // Otherwise, we want to abort rather than hand back a bad reference.
     LOG(FATAL) << msg;
   } else {
     LOG(ERROR) << msg;
   }
 }

 IndirectReferenceTable::IndirectReferenceTable(size_t max_count,
                                                IndirectRefKind desired_kind,
                                                std::string* error_msg)
     : kind_(desired_kind),
       max_entries_(max_count) {
   CHECK(error_msg != nullptr);
   CHECK_NE(desired_kind, kHandleScopeOrInvalid);

   const size_t table_bytes = max_count * sizeof(IrtEntry);
   table_mem_map_.reset(MemMap::MapAnonymous("indirect ref table", nullptr, table_bytes,
                                             PROT_READ | PROT_WRITE, false, false, error_msg));
   if (table_mem_map_.get() == nullptr && error_msg->empty()) {
     *error_msg = "Unable to map memory for indirect ref table";
   }

   if (table_mem_map_.get() != nullptr) {
     table_ = reinterpret_cast<IrtEntry*>(table_mem_map_->Begin());
   } else {
     table_ = nullptr;
   }
   segment_state_.all = IRT_FIRST_SEGMENT;
 }

 IndirectReferenceTable::~IndirectReferenceTable() {
 }

 bool IndirectReferenceTable::IsValid() const {
   return table_mem_map_.get() != nullptr;
 }

 IndirectRef IndirectReferenceTable::Add(uint32_t cookie, ObjPtr<mirror::Object> obj) {
   IRTSegmentState prevState;
   prevState.all = cookie;
   size_t topIndex = segment_state_.parts.topIndex;

   CHECK(obj != nullptr);
   VerifyObject(obj);
   DCHECK(table_ != nullptr);
   DCHECK_GE(segment_state_.parts.numHoles, prevState.parts.numHoles);

   if (topIndex == max_entries_) {
     LOG(FATAL) << "JNI ERROR (app bug): " << kind_ << " table overflow "
                << "(max=" << max_entries_ << ")\n"
                << MutatorLockedDumpable<IndirectReferenceTable>(*this);
   }

   // We know there's enough room in the table.  Now we just need to find
   // the right spot.  If there's a hole, find it and fill it; otherwise,
   // add to the end of the list.
   IndirectRef result;
   int numHoles = segment_state_.parts.numHoles - prevState.parts.numHoles;
   size_t index;
   if (numHoles > 0) {
     DCHECK_GT(topIndex, 1U);
     // Find the first hole; likely to be near the end of the list.
     IrtEntry* pScan = &table_[topIndex - 1];
     DCHECK(!pScan->GetReference()->IsNull());
     --pScan;
     while (!pScan->GetReference()->IsNull()) {
       DCHECK_GE(pScan, table_ + prevState.parts.topIndex);
       --pScan;
     }
     index = pScan - table_;
     segment_state_.parts.numHoles--;
   } else {
     // Add to the end.
     index = topIndex++;
     segment_state_.parts.topIndex = topIndex;
   }
   table_[index].Add(obj);
   result = ToIndirectRef(index);
   if ((false)) {
     LOG(INFO) << "+++ added at " << ExtractIndex(result) << " top=" << segment_state_.parts.topIndex
               << " holes=" << segment_state_.parts.numHoles;
   }

   DCHECK(result != nullptr);
   return result;
 }

 void IndirectReferenceTable::AssertEmpty() {
   for (size_t i = 0; i < Capacity(); ++i) {
     if (!table_[i].GetReference()->IsNull()) {
       LOG(FATAL) << "Internal Error: non-empty local reference table\n"
                  << MutatorLockedDumpable<IndirectReferenceTable>(*this);
       UNREACHABLE();
     }
   }
 }

 // Removes an object. We extract the table offset bits from "iref"
 // and zap the corresponding entry, leaving a hole if it's not at the top.
 // If the entry is not between the current top index and the bottom index
 // specified by the cookie, we don't remove anything. This is the behavior
 // required by JNI's DeleteLocalRef function.
 // This method is not called when a local frame is popped; this is only used
 // for explicit single removals.
 // Returns "false" if nothing was removed.
 bool IndirectReferenceTable::Remove(uint32_t cookie, IndirectRef iref) {
   IRTSegmentState prevState;
   prevState.all = cookie;
   int topIndex = segment_state_.parts.topIndex;
   int bottomIndex = prevState.parts.topIndex;

   DCHECK(table_ != nullptr);
   DCHECK_GE(segment_state_.parts.numHoles, prevState.parts.numHoles);

   if (GetIndirectRefKind(iref) == kHandleScopeOrInvalid) {
     auto* self = Thread::Current();
     if (self->HandleScopeContains(reinterpret_cast<jobject>(iref))) {
       auto* env = self->GetJniEnv();
       DCHECK(env != nullptr);
       if (env->check_jni) {
         ScopedObjectAccess soa(self);
         LOG(WARNING) << "Attempt to remove non-JNI local reference, dumping thread";
         if (kDumpStackOnNonLocalReference) {
           self->Dump(LOG_STREAM(WARNING));
         }
       }
       return true;
     }
   }
   const int idx = ExtractIndex(iref);
   if (idx < bottomIndex) {
     // Wrong segment.
     LOG(WARNING) << "Attempt to remove index outside index area (" << idx
                  << " vs " << bottomIndex << "-" << topIndex << ")";
     return false;
   }
   if (idx >= topIndex) {
     // Bad --- stale reference?
     LOG(WARNING) << "Attempt to remove invalid index " << idx
                  << " (bottom=" << bottomIndex << " top=" << topIndex << ")";
     return false;
   }

   if (idx == topIndex - 1) {
     // Top-most entry.  Scan up and consume holes.

     if (!CheckEntry("remove", iref, idx)) {
       return false;
     }

     *table_[idx].GetReference() = GcRoot<mirror::Object>(nullptr);
     int numHoles = segment_state_.parts.numHoles - prevState.parts.numHoles;
     if (numHoles != 0) {
       while (--topIndex > bottomIndex && numHoles != 0) {
         if ((false)) {
           LOG(INFO) << "+++ checking for hole at " << topIndex - 1
                     << " (cookie=" << cookie << ") val="
                     << table_[topIndex - 1].GetReference()->Read<kWithoutReadBarrier>();
         }
         if (!table_[topIndex - 1].GetReference()->IsNull()) {
           break;
         }
         if ((false)) {
           LOG(INFO) << "+++ ate hole at " << (topIndex - 1);
         }
         numHoles--;
       }
       segment_state_.parts.numHoles = numHoles + prevState.parts.numHoles;
       segment_state_.parts.topIndex = topIndex;
     } else {
       segment_state_.parts.topIndex = topIndex-1;
       if ((false)) {
         LOG(INFO) << "+++ ate last entry " << topIndex - 1;
       }
     }
   } else {
     // Not the top-most entry.  This creates a hole.  We null out the entry to prevent somebody
     // from deleting it twice and screwing up the hole count.
     if (table_[idx].GetReference()->IsNull()) {
       LOG(INFO) << "--- WEIRD: removing null entry " << idx;
       return false;
     }
     if (!CheckEntry("remove", iref, idx)) {
       return false;
     }

     *table_[idx].GetReference() = GcRoot<mirror::Object>(nullptr);
     segment_state_.parts.numHoles++;
     if ((false)) {
       LOG(INFO) << "+++ left hole at " << idx << ", holes=" << segment_state_.parts.numHoles;
     }
   }

   return true;
 }

 void IndirectReferenceTable::Trim() {
   ScopedTrace trace(__PRETTY_FUNCTION__);
   const size_t top_index = Capacity();
   auto* release_start = AlignUp(reinterpret_cast<uint8_t*>(&table_[top_index]), kPageSize);
   uint8_t* release_end = table_mem_map_->End();
   madvise(release_start, release_end - release_start, MADV_DONTNEED);
 }

 void IndirectReferenceTable::VisitRoots(RootVisitor* visitor, const RootInfo& root_info) {
   BufferedRootVisitor<kDefaultBufferedRootCount> root_visitor(visitor, root_info);
   for (auto ref : *this) {
     if (!ref->IsNull()) {
       root_visitor.VisitRoot(*ref);
       DCHECK(!ref->IsNull());
     }
   }
 }

 void IndirectReferenceTable::Dump(std::ostream& os) const {
   os << kind_ << " table dump:\n";
   ReferenceTable::Table entries;
   for (size_t i = 0; i < Capacity(); ++i) {
     ObjPtr<mirror::Object> obj = table_[i].GetReference()->Read<kWithoutReadBarrier>();
     if (obj != nullptr) {
       obj = table_[i].GetReference()->Read();
       entries.push_back(GcRoot<mirror::Object>(obj));
     }
   }
   ReferenceTable::Dump(os, entries);
 }

 }  // namespace art
	/*
	* Copyright (C) 2009 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 "indirect_reference_table-inl.h"

	#include "base/dumpable-inl.h"
	#include "base/systrace.h"
	#include "jni_internal.h"
	#include "nth_caller_visitor.h"
	#include "reference_table.h"
	#include "runtime.h"
	#include "scoped_thread_state_change-inl.h"
	#include "thread.h"
	#include "utils.h"
	#include "verify_object-inl.h"

	#include <cstdlib>

	namespace art {

	static constexpr bool kDumpStackOnNonLocalReference = false;

	const char* GetIndirectRefKindString(const IndirectRefKind& kind) {
	switch (kind) {
	case kHandleScopeOrInvalid:
	return "HandleScopeOrInvalid";
	case kLocal:
	return "Local";
	case kGlobal:
	return "Global";
	case kWeakGlobal:
	return "WeakGlobal";
	}
	return "IndirectRefKind Error";
	}

	void IndirectReferenceTable::AbortIfNoCheckJNI(const std::string& msg) {
	// If -Xcheck:jni is on, it'll give a more detailed error before aborting.
	JavaVMExt* vm = Runtime::Current()->GetJavaVM();
	if (!vm->IsCheckJniEnabled()) {
	// Otherwise, we want to abort rather than hand back a bad reference.
	LOG(FATAL) << msg;
	} else {
	LOG(ERROR) << msg;
	}
	}

	IndirectReferenceTable::IndirectReferenceTable(size_t max_count,
	IndirectRefKind desired_kind,
	std::string* error_msg)
	: kind_(desired_kind),
	max_entries_(max_count) {
	CHECK(error_msg != nullptr);
	CHECK_NE(desired_kind, kHandleScopeOrInvalid);

	const size_t table_bytes = max_count * sizeof(IrtEntry);
	table_mem_map_.reset(MemMap::MapAnonymous("indirect ref table", nullptr, table_bytes,
	PROT_READ \| PROT_WRITE, false, false, error_msg));
	if (table_mem_map_.get() == nullptr && error_msg->empty()) {
	*error_msg = "Unable to map memory for indirect ref table";
	}

	if (table_mem_map_.get() != nullptr) {
	table_ = reinterpret_cast<IrtEntry*>(table_mem_map_->Begin());
	} else {
	table_ = nullptr;
	}
	segment_state_.all = IRT_FIRST_SEGMENT;
	}

	IndirectReferenceTable::~IndirectReferenceTable() {
	}

	bool IndirectReferenceTable::IsValid() const {
	return table_mem_map_.get() != nullptr;
	}

	IndirectRef IndirectReferenceTable::Add(uint32_t cookie, ObjPtr<mirror::Object> obj) {
	IRTSegmentState prevState;
	prevState.all = cookie;
	size_t topIndex = segment_state_.parts.topIndex;

	CHECK(obj != nullptr);
	VerifyObject(obj);
	DCHECK(table_ != nullptr);
	DCHECK_GE(segment_state_.parts.numHoles, prevState.parts.numHoles);

	if (topIndex == max_entries_) {
	LOG(FATAL) << "JNI ERROR (app bug): " << kind_ << " table overflow "
	<< "(max=" << max_entries_ << ")\n"
	<< MutatorLockedDumpable<IndirectReferenceTable>(*this);
	}

	// We know there's enough room in the table. Now we just need to find
	// the right spot. If there's a hole, find it and fill it; otherwise,
	// add to the end of the list.
	IndirectRef result;
	int numHoles = segment_state_.parts.numHoles - prevState.parts.numHoles;
	size_t index;
	if (numHoles > 0) {
	DCHECK_GT(topIndex, 1U);
	// Find the first hole; likely to be near the end of the list.
	IrtEntry* pScan = &table_[topIndex - 1];
	DCHECK(!pScan->GetReference()->IsNull());
	--pScan;
	while (!pScan->GetReference()->IsNull()) {
	DCHECK_GE(pScan, table_ + prevState.parts.topIndex);
	--pScan;
	}
	index = pScan - table_;
	segment_state_.parts.numHoles--;
	} else {
	// Add to the end.
	index = topIndex++;
	segment_state_.parts.topIndex = topIndex;
	}
	table_[index].Add(obj);
	result = ToIndirectRef(index);
	if ((false)) {
	LOG(INFO) << "+++ added at " << ExtractIndex(result) << " top=" << segment_state_.parts.topIndex
	<< " holes=" << segment_state_.parts.numHoles;
	}

	DCHECK(result != nullptr);
	return result;
	}

	void IndirectReferenceTable::AssertEmpty() {
	for (size_t i = 0; i < Capacity(); ++i) {
	if (!table_[i].GetReference()->IsNull()) {
	LOG(FATAL) << "Internal Error: non-empty local reference table\n"
	<< MutatorLockedDumpable<IndirectReferenceTable>(*this);
	UNREACHABLE();
	}
	}
	}

	// Removes an object. We extract the table offset bits from "iref"
	// and zap the corresponding entry, leaving a hole if it's not at the top.
	// If the entry is not between the current top index and the bottom index
	// specified by the cookie, we don't remove anything. This is the behavior
	// required by JNI's DeleteLocalRef function.
	// This method is not called when a local frame is popped; this is only used
	// for explicit single removals.
	// Returns "false" if nothing was removed.
	bool IndirectReferenceTable::Remove(uint32_t cookie, IndirectRef iref) {
	IRTSegmentState prevState;
	prevState.all = cookie;
	int topIndex = segment_state_.parts.topIndex;
	int bottomIndex = prevState.parts.topIndex;

	DCHECK(table_ != nullptr);
	DCHECK_GE(segment_state_.parts.numHoles, prevState.parts.numHoles);

	if (GetIndirectRefKind(iref) == kHandleScopeOrInvalid) {
	auto* self = Thread::Current();
	if (self->HandleScopeContains(reinterpret_cast<jobject>(iref))) {
	auto* env = self->GetJniEnv();
	DCHECK(env != nullptr);
	if (env->check_jni) {
	ScopedObjectAccess soa(self);
	LOG(WARNING) << "Attempt to remove non-JNI local reference, dumping thread";
	if (kDumpStackOnNonLocalReference) {
	self->Dump(LOG_STREAM(WARNING));
	}
	}
	return true;
	}
	}
	const int idx = ExtractIndex(iref);
	if (idx < bottomIndex) {
	// Wrong segment.
	LOG(WARNING) << "Attempt to remove index outside index area (" << idx
	<< " vs " << bottomIndex << "-" << topIndex << ")";
	return false;
	}
	if (idx >= topIndex) {
	// Bad --- stale reference?
	LOG(WARNING) << "Attempt to remove invalid index " << idx
	<< " (bottom=" << bottomIndex << " top=" << topIndex << ")";
	return false;
	}

	if (idx == topIndex - 1) {
	// Top-most entry. Scan up and consume holes.

	if (!CheckEntry("remove", iref, idx)) {
	return false;
	}

	*table_[idx].GetReference() = GcRoot<mirror::Object>(nullptr);
	int numHoles = segment_state_.parts.numHoles - prevState.parts.numHoles;
	if (numHoles != 0) {
	while (--topIndex > bottomIndex && numHoles != 0) {
	if ((false)) {
	LOG(INFO) << "+++ checking for hole at " << topIndex - 1
	<< " (cookie=" << cookie << ") val="
	<< table_[topIndex - 1].GetReference()->Read<kWithoutReadBarrier>();
	}
	if (!table_[topIndex - 1].GetReference()->IsNull()) {
	break;
	}
	if ((false)) {
	LOG(INFO) << "+++ ate hole at " << (topIndex - 1);
	}
	numHoles--;
	}
	segment_state_.parts.numHoles = numHoles + prevState.parts.numHoles;
	segment_state_.parts.topIndex = topIndex;
	} else {
	segment_state_.parts.topIndex = topIndex-1;
	if ((false)) {
	LOG(INFO) << "+++ ate last entry " << topIndex - 1;
	}
	}
	} else {
	// Not the top-most entry. This creates a hole. We null out the entry to prevent somebody
	// from deleting it twice and screwing up the hole count.
	if (table_[idx].GetReference()->IsNull()) {
	LOG(INFO) << "--- WEIRD: removing null entry " << idx;
	return false;
	}
	if (!CheckEntry("remove", iref, idx)) {
	return false;
	}

	*table_[idx].GetReference() = GcRoot<mirror::Object>(nullptr);
	segment_state_.parts.numHoles++;
	if ((false)) {
	LOG(INFO) << "+++ left hole at " << idx << ", holes=" << segment_state_.parts.numHoles;
	}
	}

	return true;
	}

	void IndirectReferenceTable::Trim() {
	ScopedTrace trace(__PRETTY_FUNCTION__);
	const size_t top_index = Capacity();
	auto* release_start = AlignUp(reinterpret_cast<uint8_t*>(&table_[top_index]), kPageSize);
	uint8_t* release_end = table_mem_map_->End();
	madvise(release_start, release_end - release_start, MADV_DONTNEED);
	}

	void IndirectReferenceTable::VisitRoots(RootVisitor* visitor, const RootInfo& root_info) {
	BufferedRootVisitor<kDefaultBufferedRootCount> root_visitor(visitor, root_info);
	for (auto ref : *this) {
	if (!ref->IsNull()) {
	root_visitor.VisitRoot(*ref);
	DCHECK(!ref->IsNull());
	}
	}
	}

	void IndirectReferenceTable::Dump(std::ostream& os) const {
	os << kind_ << " table dump:\n";
	ReferenceTable::Table entries;
	for (size_t i = 0; i < Capacity(); ++i) {
	ObjPtr<mirror::Object> obj = table_[i].GetReference()->Read<kWithoutReadBarrier>();
	if (obj != nullptr) {
	obj = table_[i].GetReference()->Read();
	entries.push_back(GcRoot<mirror::Object>(obj));
	}
	}
	ReferenceTable::Dump(os, entries);
	}

	} // namespace art