Add SizeEstimate to CDBBatch
This allows estimating the in-memory size of a LevelDB batch.
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1 changed files with 25 additions and 1 deletions
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@ -55,11 +55,19 @@ private:
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CDataStream ssKey;
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CDataStream ssValue;
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size_t size_estimate;
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public:
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/**
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* @param[in] _parent CDBWrapper that this batch is to be submitted to
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*/
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CDBBatch(const CDBWrapper &_parent) : parent(_parent), ssKey(SER_DISK, CLIENT_VERSION), ssValue(SER_DISK, CLIENT_VERSION) { };
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CDBBatch(const CDBWrapper &_parent) : parent(_parent), ssKey(SER_DISK, CLIENT_VERSION), ssValue(SER_DISK, CLIENT_VERSION), size_estimate(0) { };
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void Clear()
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{
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batch.Clear();
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size_estimate = 0;
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}
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template <typename K, typename V>
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void Write(const K& key, const V& value)
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@ -74,6 +82,14 @@ public:
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leveldb::Slice slValue(ssValue.data(), ssValue.size());
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batch.Put(slKey, slValue);
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// LevelDB serializes writes as:
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// - byte: header
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// - varint: key length (1 byte up to 127B, 2 bytes up to 16383B, ...)
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// - byte[]: key
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// - varint: value length
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// - byte[]: value
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// The formula below assumes the key and value are both less than 16k.
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size_estimate += 3 + (slKey.size() > 127) + slKey.size() + (slValue.size() > 127) + slValue.size();
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ssKey.clear();
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ssValue.clear();
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}
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@ -86,8 +102,16 @@ public:
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leveldb::Slice slKey(ssKey.data(), ssKey.size());
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batch.Delete(slKey);
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// LevelDB serializes erases as:
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// - byte: header
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// - varint: key length
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// - byte[]: key
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// The formula below assumes the key is less than 16kB.
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size_estimate += 2 + (slKey.size() > 127) + slKey.size();
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ssKey.clear();
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}
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size_t SizeEstimate() const { return size_estimate; }
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};
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class CDBIterator
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