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authorPieter Wuille <pieter.wuille@gmail.com>2017-04-25 11:29:04 -0700
committerPieter Wuille <pieter.wuille@gmail.com>2017-05-26 13:24:24 -0700
commite66dbde6d14cb5f253b3bf8850a98f4fda2d9f49 (patch)
treedf6998e32cccf3781081d255e3430b4e71cd160f
parentb4b057a3e0712dd16b50cbcfe7d613e4413ffa1c (diff)
Add SizeEstimate to CDBBatch
This allows estimating the in-memory size of a LevelDB batch.
-rw-r--r--src/dbwrapper.h26
1 files changed, 25 insertions, 1 deletions
diff --git a/src/dbwrapper.h b/src/dbwrapper.h
index b13e98b7a4..442f37b420 100644
--- a/src/dbwrapper.h
+++ b/src/dbwrapper.h
@@ -55,11 +55,19 @@ private:
CDataStream ssKey;
CDataStream ssValue;
+ size_t size_estimate;
+
public:
/**
* @param[in] _parent CDBWrapper that this batch is to be submitted to
*/
- CDBBatch(const CDBWrapper &_parent) : parent(_parent), ssKey(SER_DISK, CLIENT_VERSION), ssValue(SER_DISK, CLIENT_VERSION) { };
+ CDBBatch(const CDBWrapper &_parent) : parent(_parent), ssKey(SER_DISK, CLIENT_VERSION), ssValue(SER_DISK, CLIENT_VERSION), size_estimate(0) { };
+
+ void Clear()
+ {
+ batch.Clear();
+ size_estimate = 0;
+ }
template <typename K, typename V>
void Write(const K& key, const V& value)
@@ -74,6 +82,14 @@ public:
leveldb::Slice slValue(ssValue.data(), ssValue.size());
batch.Put(slKey, slValue);
+ // LevelDB serializes writes as:
+ // - byte: header
+ // - varint: key length (1 byte up to 127B, 2 bytes up to 16383B, ...)
+ // - byte[]: key
+ // - varint: value length
+ // - byte[]: value
+ // The formula below assumes the key and value are both less than 16k.
+ size_estimate += 3 + (slKey.size() > 127) + slKey.size() + (slValue.size() > 127) + slValue.size();
ssKey.clear();
ssValue.clear();
}
@@ -86,8 +102,16 @@ public:
leveldb::Slice slKey(ssKey.data(), ssKey.size());
batch.Delete(slKey);
+ // LevelDB serializes erases as:
+ // - byte: header
+ // - varint: key length
+ // - byte[]: key
+ // The formula below assumes the key is less than 16kB.
+ size_estimate += 2 + (slKey.size() > 127) + slKey.size();
ssKey.clear();
}
+
+ size_t SizeEstimate() const { return size_estimate; }
};
class CDBIterator