Impala Documentation

IOBuffer* Impala::Util::ReadIOBufferFromChannel	(	Channel *	channel,
		std::string	fileName,
		std::string	useLocalFile
	)			`[inline]`

Create and an IOBuffer and fill it with data from fileName obtained via a Channel.

If useLocalFile is an empty string a memory buffer will be used, otherwise the data will be copied to the given local file.

Definition at line 17 of file ReadIOBufferFromChannel.h.

References Impala::Util::Channel::Buffer(), Impala::Util::Channel::DATA_BUFFER_SIZE, Impala::Util::Channel::GetServerInfo(), ILOG_DEBUG, ILOG_VAR, Impala::Util::Channel::LastSendHadError(), and Impala::Util::Channel::SendRequest().

Referenced by Impala::Application::Client::ExampleReadRaw(), Impala::Util::Database::GetIOBuffer(), and Impala::Persistency::FileSystem::GetIOBuffer().

00019 {
00020     ILOG_VAR(Impala.Util.ReadIOBufferFromChannel);
00021     char* buf = channel->Buffer();
00022     sprintf(buf, "openfilebuffer \"%s\" 1\0", fileName.c_str());
00023     channel->SendRequest(strlen(buf)+1);
00024     if (channel->LastSendHadError())
00025         return 0;
00026     int id = 0;
00027     Int64 bufSize = 0;
00028     sscanf(buf, "%d %lld", &id, &bufSize);
00029     ILOG_DEBUG(fileName << ", id=" << id << ", size=" << bufSize << " from "
00030                << channel->GetServerInfo());
00031 
00032     IOBuffer* ioBuf = 0;
00033     if (useLocalFile.empty())
00034         ioBuf = new IOBuffer(bufSize);
00035     else
00036         ioBuf = new IOBufferFile(useLocalFile, false, false);
00037     Int64 nrRead = 0;
00038     while (nrRead < bufSize)
00039     {
00040         sprintf(buf, "readfilebuffer %d %d\0", id, Channel::DATA_BUFFER_SIZE);
00041         int len = channel->SendRequest(strlen(buf)+1);
00042         if (channel->LastSendHadError())
00043             break;
00044         ioBuf->Write(buf, len);
00045         nrRead += len;
00046         ILOG_DEBUG("  wrote " << len << " bytes, total = " << nrRead);
00047     }
00048     sprintf(buf, "closefilebuffer %d\0", id);
00049     channel->SendRequest(strlen(buf)+1);
00050     if (useLocalFile.empty())
00051     {
00052         ioBuf->SetPosition(0); // to allow for subsequent reading by client
00053     }
00054     else
00055     {
00056         delete ioBuf;
00057         ioBuf = new IOBufferFile(useLocalFile, true, false);
00058     }
00059     return ioBuf;
00060 }

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