* Buffer reads in FdSource. Together with write buffering, this
significantly cuts down the number of syscalls (e.g., for "nix-store -qR /var/run/current-system" via the daemon, it reduced the number of syscalls in the client from 29134 to 4766 and in the daemon from 44266 to 20666).
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					 2 changed files with 32 additions and 10 deletions
				
			
		|  | @ -2,6 +2,7 @@ | |||
| #include "util.hh" | ||||
| 
 | ||||
| #include <cstring> | ||||
| #include <cerrno> | ||||
| 
 | ||||
| 
 | ||||
| namespace nix { | ||||
|  | @ -38,7 +39,28 @@ void FdSink::flush() | |||
| 
 | ||||
| void FdSource::operator () (unsigned char * data, unsigned int len) | ||||
| { | ||||
|     readFull(fd, data, len); | ||||
|     if (!buffer) buffer = new unsigned char[bufSize]; | ||||
| 
 | ||||
|     while (len) { | ||||
|         if (!bufPosIn) { | ||||
|             /* Read as much data as is available (up to the buffer
 | ||||
|                size). */ | ||||
|             checkInterrupt(); | ||||
|             ssize_t n = read(fd, (char *) buffer, bufSize); | ||||
|             if (n == -1) { | ||||
|                 if (errno == EINTR) continue; | ||||
|                 throw SysError("reading from file"); | ||||
|             } | ||||
|             if (n == 0) throw EndOfFile("unexpected end-of-file"); | ||||
|             bufPosIn = n; | ||||
|         } | ||||
|              | ||||
|         /* Copy out the data in the buffer. */ | ||||
|         size_t n = len > bufPosIn - bufPosOut ? bufPosIn - bufPosOut : len; | ||||
|         memcpy(data, buffer + bufPosOut, n); | ||||
|         data += n; bufPosOut += n; len -= n; | ||||
|         if (bufPosIn == bufPosOut) bufPosIn = bufPosOut = 0; | ||||
|     } | ||||
| } | ||||
| 
 | ||||
| 
 | ||||
|  |  | |||
|  | @ -38,9 +38,7 @@ struct FdSink : Sink | |||
|     FdSink() : fd(-1), bufSize(32 * 1024), bufPos(0), buffer(0) { } | ||||
|      | ||||
|     FdSink(int fd, unsigned int bufSize = 32 * 1024) | ||||
|         : fd(fd), bufSize(bufSize), bufPos(0), buffer(0) | ||||
|     { | ||||
|     } | ||||
|         : fd(fd), bufSize(bufSize), bufPos(0), buffer(0) { } | ||||
| 
 | ||||
|     ~FdSink() | ||||
|     { | ||||
|  | @ -58,15 +56,17 @@ struct FdSink : Sink | |||
| struct FdSource : Source | ||||
| { | ||||
|     int fd; | ||||
|     unsigned int bufSize, bufPosIn, bufPosOut; | ||||
|     unsigned char * buffer; | ||||
| 
 | ||||
|     FdSource() | ||||
|     { | ||||
|         fd = -1; | ||||
|     } | ||||
|     FdSource() : fd(-1), bufSize(32 * 1024), bufPosIn(0), bufPosOut(0), buffer(0) { } | ||||
|      | ||||
|     FdSource(int fd)  | ||||
|     FdSource(int fd, unsigned int bufSize = 32 * 1024) | ||||
|         : fd(fd), bufSize(bufSize), bufPosIn(0), bufPosOut(0), buffer(0) { } | ||||
|      | ||||
|     ~FdSource() | ||||
|     { | ||||
|         this->fd = fd; | ||||
|         if (buffer) delete[] buffer; | ||||
|     } | ||||
|      | ||||
|     void operator () (unsigned char * data, unsigned int len); | ||||
|  |  | |||
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