Update Cache::Release param from force_erase to erase_if_last_ref (#9728)

Summary:
The param name force_erase may be misleading, since the handle is erased only if it has last reference even if the param is set true.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/9728

Reviewed By: pdillinger

Differential Revision: D35038673

Pulled By: gitbw95

fbshipit-source-id: 0d16d1e8fed17b97eba7fb53207119332f659a5f

cache/clock_cache.cc

@@ -286,8 +286,8 @@ class ClockCacheShard final : public CacheShard {
     return Lookup(key, hash);
   }
   bool Release(Cache::Handle* handle, bool /*useful*/,
-               bool force_erase) override {
+               bool erase_if_last_ref) override {
-    return Release(handle, force_erase);
+    return Release(handle, erase_if_last_ref);
   }
   bool IsReady(Cache::Handle* /*handle*/) override { return true; }
   void Wait(Cache::Handle* /*handle*/) override {}
@@ -297,7 +297,7 @@ class ClockCacheShard final : public CacheShard {
   //
   // Not necessary to hold mutex_ before being called.
   bool Ref(Cache::Handle* handle) override;
-  bool Release(Cache::Handle* handle, bool force_erase = false) override;
+  bool Release(Cache::Handle* handle, bool erase_if_last_ref = false) override;
   void Erase(const Slice& key, uint32_t hash) override;
   bool EraseAndConfirm(const Slice& key, uint32_t hash,
                        CleanupContext* context);
@@ -725,11 +725,11 @@ Cache::Handle* ClockCacheShard::Lookup(const Slice& key, uint32_t hash) {
   return reinterpret_cast<Cache::Handle*>(handle);
 }
 
-bool ClockCacheShard::Release(Cache::Handle* h, bool force_erase) {
+bool ClockCacheShard::Release(Cache::Handle* h, bool erase_if_last_ref) {
   CleanupContext context;
   CacheHandle* handle = reinterpret_cast<CacheHandle*>(h);
   bool erased = Unref(handle, true, &context);
-  if (force_erase && !erased) {
+  if (erase_if_last_ref && !erased) {
     erased = EraseAndConfirm(handle->key, handle->hash, &context);
   }
   Cleanup(context);

cache/lru_cache.cc

@@ -507,7 +507,7 @@ void LRUCacheShard::SetHighPriorityPoolRatio(double high_pri_pool_ratio) {
   MaintainPoolSize();
 }
 
-bool LRUCacheShard::Release(Cache::Handle* handle, bool force_erase) {
+bool LRUCacheShard::Release(Cache::Handle* handle, bool erase_if_last_ref) {
   if (handle == nullptr) {
     return false;
   }
@@ -518,9 +518,9 @@ bool LRUCacheShard::Release(Cache::Handle* handle, bool force_erase) {
     last_reference = e->Unref();
     if (last_reference && e->InCache()) {
       // The item is still in cache, and nobody else holds a reference to it
-      if (usage_ > capacity_ || force_erase) {
+      if (usage_ > capacity_ || erase_if_last_ref) {
         // The LRU list must be empty since the cache is full
-        assert(lru_.next == &lru_ || force_erase);
+        assert(lru_.next == &lru_ || erase_if_last_ref);
         // Take this opportunity and remove the item
         table_.Remove(e->key(), e->hash);
         e->SetInCache(false);

cache/lru_cache.h

@@ -326,14 +326,14 @@ class ALIGN_AS(CACHE_LINE_SIZE) LRUCacheShard final : public CacheShard {
                   nullptr);
   }
   virtual bool Release(Cache::Handle* handle, bool /*useful*/,
-                       bool force_erase) override {
+                       bool erase_if_last_ref) override {
-    return Release(handle, force_erase);
+    return Release(handle, erase_if_last_ref);
   }
   virtual bool IsReady(Cache::Handle* /*handle*/) override;
   virtual void Wait(Cache::Handle* /*handle*/) override {}
   virtual bool Ref(Cache::Handle* handle) override;
   virtual bool Release(Cache::Handle* handle,
-                       bool force_erase = false) override;
+                       bool erase_if_last_ref = false) override;
   virtual void Erase(const Slice& key, uint32_t hash) override;
 
   // Although in some platforms the update of size_t is atomic, to make sure

cache/sharded_cache.cc

@@ -104,14 +104,15 @@ bool ShardedCache::Ref(Handle* handle) {
   return GetShard(Shard(hash))->Ref(handle);
 }
 
-bool ShardedCache::Release(Handle* handle, bool force_erase) {
+bool ShardedCache::Release(Handle* handle, bool erase_if_last_ref) {
   uint32_t hash = GetHash(handle);
-  return GetShard(Shard(hash))->Release(handle, force_erase);
+  return GetShard(Shard(hash))->Release(handle, erase_if_last_ref);
 }
 
-bool ShardedCache::Release(Handle* handle, bool useful, bool force_erase) {
+bool ShardedCache::Release(Handle* handle, bool useful,
+                           bool erase_if_last_ref) {
   uint32_t hash = GetHash(handle);
-  return GetShard(Shard(hash))->Release(handle, useful, force_erase);
+  return GetShard(Shard(hash))->Release(handle, useful, erase_if_last_ref);
 }
 
 void ShardedCache::Erase(const Slice& key) {

cache/sharded_cache.h

@@ -37,11 +37,11 @@ class CacheShard {
                                 Cache::Priority priority, bool wait,
                                 Statistics* stats) = 0;
   virtual bool Release(Cache::Handle* handle, bool useful,
-                       bool force_erase) = 0;
+                       bool erase_if_last_ref) = 0;
   virtual bool IsReady(Cache::Handle* handle) = 0;
   virtual void Wait(Cache::Handle* handle) = 0;
   virtual bool Ref(Cache::Handle* handle) = 0;
-  virtual bool Release(Cache::Handle* handle, bool force_erase) = 0;
+  virtual bool Release(Cache::Handle* handle, bool erase_if_last_ref) = 0;
   virtual void Erase(const Slice& key, uint32_t hash) = 0;
   virtual void SetCapacity(size_t capacity) = 0;
   virtual void SetStrictCapacityLimit(bool strict_capacity_limit) = 0;
@@ -94,11 +94,11 @@ class ShardedCache : public Cache {
                          const CreateCallback& create_cb, Priority priority,
                          bool wait, Statistics* stats = nullptr) override;
   virtual bool Release(Handle* handle, bool useful,
-                       bool force_erase = false) override;
+                       bool erase_if_last_ref = false) override;
   virtual bool IsReady(Handle* handle) override;
   virtual void Wait(Handle* handle) override;
   virtual bool Ref(Handle* handle) override;
-  virtual bool Release(Handle* handle, bool force_erase = false) override;
+  virtual bool Release(Handle* handle, bool erase_if_last_ref = false) override;
   virtual void Erase(const Slice& key) override;
   virtual uint64_t NewId() override;
   virtual size_t GetCapacity() const override;

db/db_bloom_filter_test.cc

@@ -919,7 +919,7 @@ class FilterConstructResPeakTrackingCache : public CacheWrapper {
   }
 
   using Cache::Release;
-  bool Release(Handle* handle, bool force_erase = false) override {
+  bool Release(Handle* handle, bool erase_if_last_ref = false) override {
     auto deleter = GetDeleter(handle);
     if (deleter == kNoopDeleterForFilterConstruction) {
       if (!last_peak_tracked_) {
@@ -929,7 +929,7 @@ class FilterConstructResPeakTrackingCache : public CacheWrapper {
       }
       cur_cache_res_ -= GetCharge(handle);
     }
-    bool is_successful = target_->Release(handle, force_erase);
+    bool is_successful = target_->Release(handle, erase_if_last_ref);
     return is_successful;
   }
 

db/db_test_util.h

@@ -894,8 +894,8 @@ class CacheWrapper : public Cache {
   bool Ref(Handle* handle) override { return target_->Ref(handle); }
 
   using Cache::Release;
-  bool Release(Handle* handle, bool force_erase = false) override {
+  bool Release(Handle* handle, bool erase_if_last_ref = false) override {
-    return target_->Release(handle, force_erase);
+    return target_->Release(handle, erase_if_last_ref);
   }
 
   void* Value(Handle* handle) override { return target_->Value(handle); }

include/rocksdb/cache.h

@@ -329,16 +329,15 @@ class Cache {
   /**
    * Release a mapping returned by a previous Lookup(). A released entry might
    * still  remain in cache in case it is later looked up by others. If
-   * force_erase is set then it also erase it from the cache if there is no
+   * erase_if_last_ref is set then it also erase it from the cache if there is
-   * other reference to  it. Erasing it should call the deleter function that
+   * no other reference to  it. Erasing it should call the deleter function that
-   * was provided when the
+   * was provided when the entry was inserted.
-   * entry was inserted.
    *
    * Returns true if the entry was also erased.
    */
   // REQUIRES: handle must not have been released yet.
   // REQUIRES: handle must have been returned by a method on *this.
-  virtual bool Release(Handle* handle, bool force_erase = false) = 0;
+  virtual bool Release(Handle* handle, bool erase_if_last_ref = false) = 0;
 
   // Return the value encapsulated in a handle returned by a
   // successful Lookup().
@@ -517,8 +516,9 @@ class Cache {
   // parameter specifies whether the data was actually used or not,
   // which may be used by the cache implementation to decide whether
   // to consider it as a hit for retention purposes.
-  virtual bool Release(Handle* handle, bool /*useful*/, bool force_erase) {
+  virtual bool Release(Handle* handle, bool /*useful*/,
-    return Release(handle, force_erase);
+                       bool erase_if_last_ref) {
+    return Release(handle, erase_if_last_ref);
   }
 
   // Determines if the handle returned by Lookup() has a valid value yet. The

table/block_based/block_based_table_reader.cc

@@ -119,7 +119,7 @@ Status ReadBlockFromFile(
 void ReleaseCachedEntry(void* arg, void* h) {
   Cache* cache = reinterpret_cast<Cache*>(arg);
   Cache::Handle* handle = reinterpret_cast<Cache::Handle*>(h);
-  cache->Release(handle, false /* force_erase */);
+  cache->Release(handle, false /* erase_if_last_ref */);
 }
 
 // For hash based index, return false if table_properties->prefix_extractor_name

table/block_based/reader_common.cc

@@ -19,7 +19,7 @@ namespace ROCKSDB_NAMESPACE {
 void ForceReleaseCachedEntry(void* arg, void* h) {
   Cache* cache = reinterpret_cast<Cache*>(arg);
   Cache::Handle* handle = reinterpret_cast<Cache::Handle*>(h);
-  cache->Release(handle, true /* force_erase */);
+  cache->Release(handle, true /* erase_if_last_ref */);
 }
 
 // WART: this is specific to block-based table

utilities/simulator_cache/sim_cache.cc

@@ -213,8 +213,8 @@ class SimCacheImpl : public SimCache {
   bool Ref(Handle* handle) override { return cache_->Ref(handle); }
 
   using Cache::Release;
-  bool Release(Handle* handle, bool force_erase = false) override {
+  bool Release(Handle* handle, bool erase_if_last_ref = false) override {
-    return cache_->Release(handle, force_erase);
+    return cache_->Release(handle, erase_if_last_ref);
   }
 
   void Erase(const Slice& key) override {