[SPARK-3941][CORE] _remainingmem should not increase twice when updateBlockInfo

In BlockManagermasterActor, _remainingMem would increase memSize for twice when updateBlockInfo if new storageLevel is invalid and old storageLevel is "useMemory". Also, _remainingMem should increase with original memory size instead of new memSize.

Author: Zhang, Liye <liye.zhang@intel.com>

Closes #2792 from liyezhang556520/spark-3941-remainMem and squashes the following commits:

3d487cc [Zhang, Liye] make the code concise
0380a32 [Zhang, Liye] [SPARK-3941][CORE] _remainingmem should not increase twice when updateBlockInfo

core/src/main/scala/org/apache/spark/storage/BlockManagerMasterActor.scala

@@ -457,16 +457,18 @@ private[spark] class BlockManagerInfo(
 
     if (_blocks.containsKey(blockId)) {
       // The block exists on the slave already.
-      val originalLevel: StorageLevel = _blocks.get(blockId).storageLevel
+      val blockStatus: BlockStatus = _blocks.get(blockId)
+      val originalLevel: StorageLevel = blockStatus.storageLevel
+      val originalMemSize: Long = blockStatus.memSize
 
       if (originalLevel.useMemory) {
-        _remainingMem += memSize
+        _remainingMem += originalMemSize
       }
     }
 
     if (storageLevel.isValid) {
       /* isValid means it is either stored in-memory, on-disk or on-Tachyon.
-       * But the memSize here indicates the data size in or dropped from memory,
+       * The memSize here indicates the data size in or dropped from memory,
        * tachyonSize here indicates the data size in or dropped from Tachyon,
        * and the diskSize here indicates the data size in or dropped to disk.
        * They can be both larger than 0, when a block is dropped from memory to disk.
@@ -493,7 +495,6 @@ private[spark] class BlockManagerInfo(
       val blockStatus: BlockStatus = _blocks.get(blockId)
       _blocks.remove(blockId)
       if (blockStatus.storageLevel.useMemory) {
-        _remainingMem += blockStatus.memSize
         logInfo("Removed %s on %s in memory (size: %s, free: %s)".format(
           blockId, blockManagerId.hostPort, Utils.bytesToString(blockStatus.memSize),
           Utils.bytesToString(_remainingMem)))