github.com/m3db/m3@v1.5.0/src/dbnode/x/xio/types.go (about)

     1  // Copyright (c) 2016 Uber Technologies, Inc.
     2  //
     3  // Permission is hereby granted, free of charge, to any person obtaining a copy
     4  // of this software and associated documentation files (the "Software"), to deal
     5  // in the Software without restriction, including without limitation the rights
     6  // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
     7  // copies of the Software, and to permit persons to whom the Software is
     8  // furnished to do so, subject to the following conditions:
     9  //
    10  // The above copyright notice and this permission notice shall be included in
    11  // all copies or substantial portions of the Software.
    12  //
    13  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    14  // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
    15  // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
    16  // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
    17  // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
    18  // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
    19  // THE SOFTWARE.
    20  
    21  package xio
    22  
    23  import (
    24  	"time"
    25  
    26  	"github.com/m3db/m3/src/dbnode/ts"
    27  	"github.com/m3db/m3/src/x/pool"
    28  	xresource "github.com/m3db/m3/src/x/resource"
    29  	xtime "github.com/m3db/m3/src/x/time"
    30  )
    31  
    32  // BlockReader represents a block reader backed by a
    33  // SegmentReader with start time and block size.
    34  type BlockReader struct {
    35  	SegmentReader
    36  	Start     xtime.UnixNano
    37  	BlockSize time.Duration
    38  }
    39  
    40  // EmptyBlockReader represents the default block reader.
    41  var EmptyBlockReader = BlockReader{}
    42  
    43  // SegmentReader implements the io reader interface backed by a segment.
    44  type SegmentReader interface {
    45  	Reader64
    46  	xresource.Finalizer
    47  
    48  	// Segment gets the segment read by this reader.
    49  	Segment() (ts.Segment, error)
    50  
    51  	// Reset resets the reader to read a new segment.
    52  	Reset(segment ts.Segment)
    53  
    54  	// Clone returns a clone of a copy of the underlying data reset,
    55  	// with an optional byte pool to reduce allocations.
    56  	Clone(pool pool.CheckedBytesPool) (SegmentReader, error)
    57  }
    58  
    59  // SegmentReaderPool provides a pool for segment readers.
    60  type SegmentReaderPool interface {
    61  	// Init will initialize the pool.
    62  	Init()
    63  
    64  	// Get provides a segment reader from the pool.
    65  	Get() SegmentReader
    66  
    67  	// Put returns a segment reader to the pool.
    68  	Put(sr SegmentReader)
    69  }
    70  
    71  // ReaderSliceOfSlicesIterator is an iterator that iterates
    72  // through an array of reader arrays.
    73  type ReaderSliceOfSlicesIterator interface {
    74  	// Next moves to the next item.
    75  	Next() bool
    76  
    77  	// CurrentReaders returns the current length, start time, and block size.
    78  	CurrentReaders() (length int, start xtime.UnixNano, blockSize time.Duration)
    79  
    80  	// CurrentReaderAt returns the current reader in the slice
    81  	// of readers at an index.
    82  	CurrentReaderAt(idx int) BlockReader
    83  
    84  	// Close closes the iterator.
    85  	Close()
    86  
    87  	// Size gives the size of bytes in this iterator.
    88  	Size() (int, error)
    89  
    90  	// RewindToIndex returns the iterator to a specific index.
    91  	// This operation is invalid if any of the block readers have been read.
    92  	RewindToIndex(idx int)
    93  
    94  	// Index returns the iterator's current index.
    95  	Index() int
    96  }
    97  
    98  // ReaderSliceOfSlicesFromBlockReadersIterator is an iterator
    99  // that iterates through an array of reader arrays.
   100  type ReaderSliceOfSlicesFromBlockReadersIterator interface {
   101  	ReaderSliceOfSlicesIterator
   102  
   103  	// Reset resets the iterator with a new array of block readers arrays.
   104  	Reset(blocks [][]BlockReader)
   105  }
   106  
   107  // Reader64 is a reader for reading 64 bit words.
   108  type Reader64 interface {
   109  
   110  	// Read64 reads and returns a 64 bit word plus a number of bytes (up to 8) actually read.
   111  	Read64() (word uint64, n byte, err error)
   112  
   113  	// Read64 peeks and returns the next 64 bit word plus a number of bytes (up to 8) available.
   114  	Peek64() (word uint64, n byte, err error)
   115  }