github.com/anjalikarhana/fabric@v2.1.1+incompatible/common/ledger/blkstorage/fsblkstorage/blocks_itr.go (about)

     1  /*
     2  Copyright IBM Corp. 2016 All Rights Reserved.
     3  
     4  Licensed under the Apache License, Version 2.0 (the "License");
     5  you may not use this file except in compliance with the License.
     6  You may obtain a copy of the License at
     7  
     8  		 http://www.apache.org/licenses/LICENSE-2.0
     9  
    10  Unless required by applicable law or agreed to in writing, software
    11  distributed under the License is distributed on an "AS IS" BASIS,
    12  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13  See the License for the specific language governing permissions and
    14  limitations under the License.
    15  */
    16  
    17  package fsblkstorage
    18  
    19  import (
    20  	"sync"
    21  
    22  	"github.com/hyperledger/fabric/common/ledger"
    23  )
    24  
    25  // blocksItr - an iterator for iterating over a sequence of blocks
    26  type blocksItr struct {
    27  	mgr                  *blockfileMgr
    28  	maxBlockNumAvailable uint64
    29  	blockNumToRetrieve   uint64
    30  	stream               *blockStream
    31  	closeMarker          bool
    32  	closeMarkerLock      *sync.Mutex
    33  }
    34  
    35  func newBlockItr(mgr *blockfileMgr, startBlockNum uint64) *blocksItr {
    36  	mgr.cpInfoCond.L.Lock()
    37  	defer mgr.cpInfoCond.L.Unlock()
    38  	return &blocksItr{mgr, mgr.cpInfo.lastBlockNumber, startBlockNum, nil, false, &sync.Mutex{}}
    39  }
    40  
    41  func (itr *blocksItr) waitForBlock(blockNum uint64) uint64 {
    42  	itr.mgr.cpInfoCond.L.Lock()
    43  	defer itr.mgr.cpInfoCond.L.Unlock()
    44  	for itr.mgr.cpInfo.lastBlockNumber < blockNum && !itr.shouldClose() {
    45  		logger.Debugf("Going to wait for newer blocks. maxAvailaBlockNumber=[%d], waitForBlockNum=[%d]",
    46  			itr.mgr.cpInfo.lastBlockNumber, blockNum)
    47  		itr.mgr.cpInfoCond.Wait()
    48  		logger.Debugf("Came out of wait. maxAvailaBlockNumber=[%d]", itr.mgr.cpInfo.lastBlockNumber)
    49  	}
    50  	return itr.mgr.cpInfo.lastBlockNumber
    51  }
    52  
    53  func (itr *blocksItr) initStream() error {
    54  	var lp *fileLocPointer
    55  	var err error
    56  	if lp, err = itr.mgr.index.getBlockLocByBlockNum(itr.blockNumToRetrieve); err != nil {
    57  		return err
    58  	}
    59  	if itr.stream, err = newBlockStream(itr.mgr.rootDir, lp.fileSuffixNum, int64(lp.offset), -1); err != nil {
    60  		return err
    61  	}
    62  	return nil
    63  }
    64  
    65  func (itr *blocksItr) shouldClose() bool {
    66  	itr.closeMarkerLock.Lock()
    67  	defer itr.closeMarkerLock.Unlock()
    68  	return itr.closeMarker
    69  }
    70  
    71  // Next moves the cursor to next block and returns true iff the iterator is not exhausted
    72  func (itr *blocksItr) Next() (ledger.QueryResult, error) {
    73  	if itr.maxBlockNumAvailable < itr.blockNumToRetrieve {
    74  		itr.maxBlockNumAvailable = itr.waitForBlock(itr.blockNumToRetrieve)
    75  	}
    76  	itr.closeMarkerLock.Lock()
    77  	defer itr.closeMarkerLock.Unlock()
    78  	if itr.closeMarker {
    79  		return nil, nil
    80  	}
    81  	if itr.stream == nil {
    82  		logger.Debugf("Initializing block stream for iterator. itr.maxBlockNumAvailable=%d", itr.maxBlockNumAvailable)
    83  		if err := itr.initStream(); err != nil {
    84  			return nil, err
    85  		}
    86  	}
    87  	nextBlockBytes, err := itr.stream.nextBlockBytes()
    88  	if err != nil {
    89  		return nil, err
    90  	}
    91  	itr.blockNumToRetrieve++
    92  	return deserializeBlock(nextBlockBytes)
    93  }
    94  
    95  // Close releases any resources held by the iterator
    96  func (itr *blocksItr) Close() {
    97  	itr.mgr.cpInfoCond.L.Lock()
    98  	defer itr.mgr.cpInfoCond.L.Unlock()
    99  	itr.closeMarkerLock.Lock()
   100  	defer itr.closeMarkerLock.Unlock()
   101  	itr.closeMarker = true
   102  	itr.mgr.cpInfoCond.Broadcast()
   103  	if itr.stream != nil {
   104  		itr.stream.close()
   105  	}
   106  }