github.com/lirm/aeron-go@v0.0.0-20230415210743-920325491dc4/aeron/logbuffer/term/reader.go (about)

     1  /*
     2  Copyright 2016 Stanislav Liberman
     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 term
    18  
    19  import (
    20  	"github.com/lirm/aeron-go/aeron/atomic"
    21  	"github.com/lirm/aeron-go/aeron/logbuffer"
    22  	"github.com/lirm/aeron-go/aeron/util"
    23  )
    24  
    25  // Read will attempt to read the next frame from the term and invoke the callback if successful.
    26  // Method will return a tuple of new term offset and number of fragments read
    27  //
    28  //go:norace
    29  func Read(termBuffer *atomic.Buffer, termOffset int32, handler FragmentHandler, fragmentLimit int,
    30  	header *logbuffer.Header) (int32, int) {
    31  
    32  	capacity := termBuffer.Capacity()
    33  
    34  	var fragmentsRead int
    35  	for fragmentsRead < fragmentLimit && termOffset < capacity {
    36  		frameLength := logbuffer.GetFrameLength(termBuffer, termOffset)
    37  		if frameLength <= 0 {
    38  			break
    39  		}
    40  
    41  		fragmentOffset := termOffset
    42  		termOffset += util.AlignInt32(frameLength, logbuffer.FrameAlignment)
    43  
    44  		if !logbuffer.IsPaddingFrame(termBuffer, fragmentOffset) {
    45  			header.Wrap(termBuffer.Ptr(), termBuffer.Capacity())
    46  			header.SetOffset(fragmentOffset)
    47  			handler(termBuffer, fragmentOffset+logbuffer.DataFrameHeader.Length,
    48  				frameLength-logbuffer.DataFrameHeader.Length, header)
    49  
    50  			fragmentsRead++
    51  		}
    52  	}
    53  
    54  	return termOffset, fragmentsRead
    55  }
    56  
    57  // BoundedRead will attempt to read frames from the term up to the specified offsetLimit.
    58  // Method will return a tuple of new term offset and number of fragments read
    59  func BoundedRead(termBuffer *atomic.Buffer, termOffset int32, offsetLimit int32, handler FragmentHandler,
    60  	fragmentLimit int, header *logbuffer.Header) (int32, int) {
    61  
    62  	var fragmentsRead int
    63  	for fragmentsRead < fragmentLimit && termOffset < offsetLimit {
    64  		frameLength := logbuffer.GetFrameLength(termBuffer, termOffset)
    65  		if frameLength <= 0 {
    66  			break
    67  		}
    68  
    69  		fragmentOffset := termOffset
    70  		termOffset += util.AlignInt32(frameLength, logbuffer.FrameAlignment)
    71  
    72  		if !logbuffer.IsPaddingFrame(termBuffer, fragmentOffset) {
    73  			header.Wrap(termBuffer.Ptr(), termBuffer.Capacity())
    74  			header.SetOffset(fragmentOffset)
    75  			handler(termBuffer, fragmentOffset+logbuffer.DataFrameHeader.Length,
    76  				frameLength-logbuffer.DataFrameHeader.Length, header)
    77  
    78  			fragmentsRead++
    79  		}
    80  	}
    81  
    82  	return termOffset, fragmentsRead
    83  }