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diff --git a/deps/v8/src/base/hashmap.h b/deps/v8/src/base/hashmap.h
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+++ b/deps/v8/src/base/hashmap.h
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+// Copyright 2012 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// The reason we write our own hash map instead of using unordered_map in STL,
+// is that STL containers use a mutex pool on debug build, which will lead to
+// deadlock when we are using async signal handler.
+
+#ifndef V8_BASE_HASHMAP_H_
+#define V8_BASE_HASHMAP_H_
+
+#include <stdlib.h>
+
+#include "src/base/bits.h"
+#include "src/base/logging.h"
+
+namespace v8 {
+namespace base {
+
+class DefaultAllocationPolicy {
+ public:
+  V8_INLINE void* New(size_t size) { return malloc(size); }
+  V8_INLINE static void Delete(void* p) { free(p); }
+};
+
+template <class AllocationPolicy>
+class TemplateHashMapImpl {
+ public:
+  typedef bool (*MatchFun)(void* key1, void* key2);
+
+  // The default capacity.  This is used by the call sites which want
+  // to pass in a non-default AllocationPolicy but want to use the
+  // default value of capacity specified by the implementation.
+  static const uint32_t kDefaultHashMapCapacity = 8;
+
+  // initial_capacity is the size of the initial hash map;
+  // it must be a power of 2 (and thus must not be 0).
+  TemplateHashMapImpl(MatchFun match,
+                      uint32_t capacity = kDefaultHashMapCapacity,
+                      AllocationPolicy allocator = AllocationPolicy());
+
+  ~TemplateHashMapImpl();
+
+  // HashMap entries are (key, value, hash) triplets.
+  // Some clients may not need to use the value slot
+  // (e.g. implementers of sets, where the key is the value).
+  struct Entry {
+    void* key;
+    void* value;
+    uint32_t hash;  // The full hash value for key
+  };
+
+  // If an entry with matching key is found, returns that entry.
+  // Otherwise, NULL is returned.
+  Entry* Lookup(void* key, uint32_t hash) const;
+
+  // If an entry with matching key is found, returns that entry.
+  // If no matching entry is found, a new entry is inserted with
+  // corresponding key, key hash, and NULL value.
+  Entry* LookupOrInsert(void* key, uint32_t hash,
+                        AllocationPolicy allocator = AllocationPolicy());
+
+  Entry* InsertNew(void* key, uint32_t hash,
+                   AllocationPolicy allocator = AllocationPolicy());
+
+  // Removes the entry with matching key.
+  // It returns the value of the deleted entry
+  // or null if there is no value for such key.
+  void* Remove(void* key, uint32_t hash);
+
+  // Empties the hash map (occupancy() == 0).
+  void Clear();
+
+  // The number of (non-empty) entries in the table.
+  uint32_t occupancy() const { return occupancy_; }
+
+  // The capacity of the table. The implementation
+  // makes sure that occupancy is at most 80% of
+  // the table capacity.
+  uint32_t capacity() const { return capacity_; }
+
+  // Iteration
+  //
+  // for (Entry* p = map.Start(); p != NULL; p = map.Next(p)) {
+  //   ...
+  // }
+  //
+  // If entries are inserted during iteration, the effect of
+  // calling Next() is undefined.
+  Entry* Start() const;
+  Entry* Next(Entry* p) const;
+
+  // Some match functions defined for convenience.
+  static bool PointersMatch(void* key1, void* key2) { return key1 == key2; }
+
+ private:
+  MatchFun match_;
+  Entry* map_;
+  uint32_t capacity_;
+  uint32_t occupancy_;
+
+  Entry* map_end() const { return map_ + capacity_; }
+  Entry* Probe(void* key, uint32_t hash) const;
+  void Initialize(uint32_t capacity, AllocationPolicy allocator);
+  void Resize(AllocationPolicy allocator);
+};
+
+typedef TemplateHashMapImpl<DefaultAllocationPolicy> HashMap;
+
+template <class AllocationPolicy>
+TemplateHashMapImpl<AllocationPolicy>::TemplateHashMapImpl(
+    MatchFun match, uint32_t initial_capacity, AllocationPolicy allocator) {
+  match_ = match;
+  Initialize(initial_capacity, allocator);
+}
+
+template <class AllocationPolicy>
+TemplateHashMapImpl<AllocationPolicy>::~TemplateHashMapImpl() {
+  AllocationPolicy::Delete(map_);
+}
+
+template <class AllocationPolicy>
+typename TemplateHashMapImpl<AllocationPolicy>::Entry*
+TemplateHashMapImpl<AllocationPolicy>::Lookup(void* key, uint32_t hash) const {
+  Entry* p = Probe(key, hash);
+  return p->key != NULL ? p : NULL;
+}
+
+template <class AllocationPolicy>
+typename TemplateHashMapImpl<AllocationPolicy>::Entry*
+TemplateHashMapImpl<AllocationPolicy>::LookupOrInsert(
+    void* key, uint32_t hash, AllocationPolicy allocator) {
+  // Find a matching entry.
+  Entry* p = Probe(key, hash);
+  if (p->key != NULL) {
+    return p;
+  }
+
+  return InsertNew(key, hash, allocator);
+}
+
+template <class AllocationPolicy>
+typename TemplateHashMapImpl<AllocationPolicy>::Entry*
+TemplateHashMapImpl<AllocationPolicy>::InsertNew(void* key, uint32_t hash,
+                                                 AllocationPolicy allocator) {
+  // Find a matching entry.
+  Entry* p = Probe(key, hash);
+  DCHECK(p->key == NULL);
+
+  // No entry found; insert one.
+  p->key = key;
+  p->value = NULL;
+  p->hash = hash;
+  occupancy_++;
+
+  // Grow the map if we reached >= 80% occupancy.
+  if (occupancy_ + occupancy_ / 4 >= capacity_) {
+    Resize(allocator);
+    p = Probe(key, hash);
+  }
+
+  return p;
+}
+
+template <class AllocationPolicy>
+void* TemplateHashMapImpl<AllocationPolicy>::Remove(void* key, uint32_t hash) {
+  // Lookup the entry for the key to remove.
+  Entry* p = Probe(key, hash);
+  if (p->key == NULL) {
+    // Key not found nothing to remove.
+    return NULL;
+  }
+
+  void* value = p->value;
+  // To remove an entry we need to ensure that it does not create an empty
+  // entry that will cause the search for another entry to stop too soon. If all
+  // the entries between the entry to remove and the next empty slot have their
+  // initial position inside this interval, clearing the entry to remove will
+  // not break the search. If, while searching for the next empty entry, an
+  // entry is encountered which does not have its initial position between the
+  // entry to remove and the position looked at, then this entry can be moved to
+  // the place of the entry to remove without breaking the search for it. The
+  // entry made vacant by this move is now the entry to remove and the process
+  // starts over.
+  // Algorithm from http://en.wikipedia.org/wiki/Open_addressing.
+
+  // This guarantees loop termination as there is at least one empty entry so
+  // eventually the removed entry will have an empty entry after it.
+  DCHECK(occupancy_ < capacity_);
+
+  // p is the candidate entry to clear. q is used to scan forwards.
+  Entry* q = p;  // Start at the entry to remove.
+  while (true) {
+    // Move q to the next entry.
+    q = q + 1;
+    if (q == map_end()) {
+      q = map_;
+    }
+
+    // All entries between p and q have their initial position between p and q
+    // and the entry p can be cleared without breaking the search for these
+    // entries.
+    if (q->key == NULL) {
+      break;
+    }
+
+    // Find the initial position for the entry at position q.
+    Entry* r = map_ + (q->hash & (capacity_ - 1));
+
+    // If the entry at position q has its initial position outside the range
+    // between p and q it can be moved forward to position p and will still be
+    // found. There is now a new candidate entry for clearing.
+    if ((q > p && (r <= p || r > q)) || (q < p && (r <= p && r > q))) {
+      *p = *q;
+      p = q;
+    }
+  }
+
+  // Clear the entry which is allowed to en emptied.
+  p->key = NULL;
+  occupancy_--;
+  return value;
+}
+
+template <class AllocationPolicy>
+void TemplateHashMapImpl<AllocationPolicy>::Clear() {
+  // Mark all entries as empty.
+  const Entry* end = map_end();
+  for (Entry* p = map_; p < end; p++) {
+    p->key = NULL;
+  }
+  occupancy_ = 0;
+}
+
+template <class AllocationPolicy>
+typename TemplateHashMapImpl<AllocationPolicy>::Entry*
+TemplateHashMapImpl<AllocationPolicy>::Start() const {
+  return Next(map_ - 1);
+}
+
+template <class AllocationPolicy>
+typename TemplateHashMapImpl<AllocationPolicy>::Entry*
+TemplateHashMapImpl<AllocationPolicy>::Next(Entry* p) const {
+  const Entry* end = map_end();
+  DCHECK(map_ - 1 <= p && p < end);
+  for (p++; p < end; p++) {
+    if (p->key != NULL) {
+      return p;
+    }
+  }
+  return NULL;
+}
+
+template <class AllocationPolicy>
+typename TemplateHashMapImpl<AllocationPolicy>::Entry*
+TemplateHashMapImpl<AllocationPolicy>::Probe(void* key, uint32_t hash) const {
+  DCHECK(key != NULL);
+
+  DCHECK(base::bits::IsPowerOfTwo32(capacity_));
+  Entry* p = map_ + (hash & (capacity_ - 1));
+  const Entry* end = map_end();
+  DCHECK(map_ <= p && p < end);
+
+  DCHECK(occupancy_ < capacity_);  // Guarantees loop termination.
+  while (p->key != NULL && (hash != p->hash || !match_(key, p->key))) {
+    p++;
+    if (p >= end) {
+      p = map_;
+    }
+  }
+
+  return p;
+}
+
+template <class AllocationPolicy>
+void TemplateHashMapImpl<AllocationPolicy>::Initialize(
+    uint32_t capacity, AllocationPolicy allocator) {
+  DCHECK(base::bits::IsPowerOfTwo32(capacity));
+  map_ = reinterpret_cast<Entry*>(allocator.New(capacity * sizeof(Entry)));
+  if (map_ == NULL) {
+    FATAL("Out of memory: HashMap::Initialize");
+    return;
+  }
+  capacity_ = capacity;
+  Clear();
+}
+
+template <class AllocationPolicy>
+void TemplateHashMapImpl<AllocationPolicy>::Resize(AllocationPolicy allocator) {
+  Entry* map = map_;
+  uint32_t n = occupancy_;
+
+  // Allocate larger map.
+  Initialize(capacity_ * 2, allocator);
+
+  // Rehash all current entries.
+  for (Entry* p = map; n > 0; p++) {
+    if (p->key != NULL) {
+      Entry* entry = LookupOrInsert(p->key, p->hash, allocator);
+      entry->value = p->value;
+      n--;
+    }
+  }
+
+  // Delete old map.
+  AllocationPolicy::Delete(map);
+}
+
+// A hash map for pointer keys and values with an STL-like interface.
+template <class Key, class Value, class AllocationPolicy>
+class TemplateHashMap : private TemplateHashMapImpl<AllocationPolicy> {
+ public:
+  STATIC_ASSERT(sizeof(Key*) == sizeof(void*));    // NOLINT
+  STATIC_ASSERT(sizeof(Value*) == sizeof(void*));  // NOLINT
+  struct value_type {
+    Key* first;
+    Value* second;
+  };
+
+  class Iterator {
+   public:
+    Iterator& operator++() {
+      entry_ = map_->Next(entry_);
+      return *this;
+    }
+
+    value_type* operator->() { return reinterpret_cast<value_type*>(entry_); }
+    bool operator!=(const Iterator& other) { return entry_ != other.entry_; }
+
+   private:
+    Iterator(const TemplateHashMapImpl<AllocationPolicy>* map,
+             typename TemplateHashMapImpl<AllocationPolicy>::Entry* entry)
+        : map_(map), entry_(entry) {}
+
+    const TemplateHashMapImpl<AllocationPolicy>* map_;
+    typename TemplateHashMapImpl<AllocationPolicy>::Entry* entry_;
+
+    friend class TemplateHashMap;
+  };
+
+  TemplateHashMap(
+      typename TemplateHashMapImpl<AllocationPolicy>::MatchFun match,
+      AllocationPolicy allocator = AllocationPolicy())
+      : TemplateHashMapImpl<AllocationPolicy>(
+            match,
+            TemplateHashMapImpl<AllocationPolicy>::kDefaultHashMapCapacity,
+            allocator) {}
+
+  Iterator begin() const { return Iterator(this, this->Start()); }
+  Iterator end() const { return Iterator(this, NULL); }
+  Iterator find(Key* key, bool insert = false,
+                AllocationPolicy allocator = AllocationPolicy()) {
+    if (insert) {
+      return Iterator(this, this->LookupOrInsert(key, key->Hash(), allocator));
+    }
+    return Iterator(this, this->Lookup(key, key->Hash()));
+  }
+};
+
+}  // namespace base
+}  // namespace v8
+
+#endif  // V8_BASE_HASHMAP_H_