I have implemented my system following your suggestion.
On Aug 11, 5:36 pm, Jason Hsueh <jas...@google.com> wrote:
> ParseFromFileDescriptor will read until there is no more input. This is
> consistent with behavior when parsing from other types of input streams, as
> the message wire format is not self delimiting. For file descriptors, that
> means you have to reach EOF. As such, ParseFromFileDescriptor is only useful
> when the whole file contains a single message.
> One approach to writing multiple messages to the same stream is to use a
> length-delimited format: write the size of the message, then serialize the
> message itself. On the receiver side, you would set up a FileInputStream,
> and wrap a CodedInputStream around that. You can read the size of the
> messages from the stream and then use PushLimit and PopLimit to control how
> much data is read.
> On Wed, Aug 11, 2010 at 2:19 PM, nirajshr <niraj...@gmail.com> wrote:
> > Hi Kenton,
> > I really appreciate your quick response. As you mentioned in your
> > response, the protobuf library does write all the data to the file
> > descriptor before returning from SerializeToFileDescriptor(). But, I
> > have to explicitly close the file descriptor (using close(fd) ) before
> > the data gets flushed. As a result, ParseFromFileDescriptor keeps
> > waiting for the input until the file descriptor has been closed.
> > I tried breaking this process into two parts to see if the problem
> > persists:
> > In the first program,
> > 1) Firstly, I used the SerializeToString() function to write to a
> > string,
> > 2) Then, I wrote the string to a file descriptor using the
> > write(char*, buffer length) function.
> > Then, I tested the following two ways to receive the data at the other
> > end of the socket:
> > In second program,
> > 1) I used ParseFromFileDescriptor() function to receive the data. The
> > problem persisted in this case. The first program had to call
> > close(fd) in order for the second program to receive the data.
> > 2) Alternatively, I used read(char* str, buff_len) &
> > ParseFromString() functions to receive the data. In this case, the
> > program immediately received the data, without having to close the
> > file descriptor in the first program.
> > I know that this issue might be outside the scope of google protocol
> > buffers. But, this contradictory results show that the
> > ParseFromFileDescriptor() function expects an explicit close of the
> > filedescriptor before it can retrieve all the data. I guess this makes
> > sense as ParseFromFileDescriptor() function has no way of knowing the
> > length of the data. Having to close the file descriptor as a way to
> > mark the end of the transmission of data is confusing. The
> > SerializeToFileDescriptor() function has to take care of this so that
> > ParseFromFileDescriptor() function has an idea about the size of data
> > being received.
> > I am sorry to bother you with this long post, but, your insight will
> > be very helpful.
> > On Aug 10, 5:40 pm, Kenton Varda <ken...@google.com> wrote:
> > > The protobuf library writes all data to the file descriptor before
> > returning
> > > from SerializeToFileDescriptor(). So, the problem is not in protobufs.
> > > Sorry.
> > > On Tue, Aug 10, 2010 at 10:58 AM, nirajshr <niraj...@gmail.com> wrote:
> > > > Particularly, I am using the SerializeToFileDescriptor() function to
> > > > send the serialized data over a socket interface. The problem is that
> > > > the data does not get sent before I explicitly close the socket using
> > > > close(fileDescriptor). I even tried letting the google protocol buffer
> > > > object go out of scope (hoping the destructor would be called, and
> > > > hence flushing of the data). I am sending large amounts of data
> > > > (around 1MB). I did not face this problem while sending smaller amount
> > > > of data.
> > > > Isn't there any way I can force flushing of data without destroying
> > > > the google protocol buffer object?
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