* Buffer writes in FdSink. This significantly reduces the number of

system calls / context switches when dumping a NAR and in the worker
  protocol.
This commit is contained in:
Eelco Dolstra 2011-12-14 23:30:06 +00:00
parent 893cac1402
commit 3a48282b06
4 changed files with 51 additions and 15 deletions

View file

@ -65,6 +65,7 @@ void RemoteStore::openConnection()
/* Send the magic greeting, check for the reply. */
try {
writeInt(WORKER_MAGIC_1, to);
to.flush();
unsigned int magic = readInt(from);
if (magic != WORKER_MAGIC_2) throw Error("protocol mismatch");
@ -166,6 +167,7 @@ void RemoteStore::connectToDaemon()
RemoteStore::~RemoteStore()
{
try {
to.flush();
fdSocket.close();
if (child != -1)
child.wait(true);
@ -488,6 +490,7 @@ void RemoteStore::clearFailedPaths(const PathSet & paths)
void RemoteStore::processStderr(Sink * sink, Source * source)
{
to.flush();
unsigned int msg;
while ((msg = readInt(from)) == STDERR_NEXT
|| msg == STDERR_READ || msg == STDERR_WRITE) {
@ -503,6 +506,7 @@ void RemoteStore::processStderr(Sink * sink, Source * source)
AutoDeleteArray<unsigned char> d(buf);
(*source)(buf, len);
writeString(string((const char *) buf, len), to);
to.flush();
}
else {
string s = readString(from);

View file

@ -9,7 +9,30 @@ namespace nix {
void FdSink::operator () (const unsigned char * data, unsigned int len)
{
if (!buffer) buffer = new unsigned char[bufSize];
while (len) {
/* Optimisation: bypass the buffer if the data exceeds the
buffer size and there is no unflushed data. */
if (bufPos == 0 && len >= bufSize) {
writeFull(fd, data, len);
break;
}
/* Otherwise, copy the bytes to the buffer. Flush the buffer
when it's full. */
size_t n = bufPos + len > bufSize ? bufSize - bufPos : len;
memcpy(buffer + bufPos, data, n);
data += n; bufPos += n; len -= n;
if (bufPos == bufSize) flush();
}
}
void FdSink::flush()
{
if (fd == -1 || bufPos == 0) return;
writeFull(fd, buffer, bufPos);
bufPos = 0;
}

View file

@ -28,22 +28,29 @@ struct Source
};
/* A sink that writes data to a file descriptor. */
/* A sink that writes data to a file descriptor (using a buffer). */
struct FdSink : Sink
{
int fd;
unsigned int bufSize, bufPos;
unsigned char * buffer;
FdSink()
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 = -1;
}
FdSink(int fd)
~FdSink()
{
this->fd = fd;
flush();
if (buffer) delete[] buffer;
}
void operator () (const unsigned char * data, unsigned int len);
void flush();
};

View file

@ -57,6 +57,7 @@ static void tunnelStderr(const unsigned char * buf, size_t count)
try {
writeInt(STDERR_NEXT, to);
writeString(string((char *) buf, count), to);
to.flush();
} catch (...) {
/* Write failed; that means that the other side is
gone. */
@ -200,9 +201,7 @@ static void stopWork(bool success = true, const string & msg = "", unsigned int
struct TunnelSink : Sink
{
Sink & to;
TunnelSink(Sink & to) : to(to)
{
}
TunnelSink(Sink & to) : to(to) { }
virtual void operator ()
(const unsigned char * data, unsigned int len)
{
@ -215,9 +214,7 @@ struct TunnelSink : Sink
struct TunnelSource : Source
{
Source & from;
TunnelSource(Source & from) : from(from)
{
}
TunnelSource(Source & from) : from(from) { }
virtual void operator ()
(unsigned char * data, unsigned int len)
{
@ -228,6 +225,7 @@ struct TunnelSource : Source
writeInt(STDERR_READ, to);
writeInt(len, to);
to.flush();
string s = readString(from);
if (s.size() != len) throw Error("not enough data");
memcpy(data, (const unsigned char *) s.c_str(), len);
@ -596,8 +594,8 @@ static void processConnection()
unsigned int magic = readInt(from);
if (magic != WORKER_MAGIC_1) throw Error("protocol mismatch");
writeInt(WORKER_MAGIC_2, to);
writeInt(PROTOCOL_VERSION, to);
to.flush();
unsigned int clientVersion = readInt(from);
/* Send startup error messages to the client. */
@ -619,9 +617,11 @@ static void processConnection()
store = boost::shared_ptr<StoreAPI>(new LocalStore());
stopWork();
to.flush();
} catch (Error & e) {
stopWork(false, e.msg());
to.flush();
return;
}
@ -652,6 +652,8 @@ static void processConnection()
if (!errorAllowed) break;
}
to.flush();
assert(!canSendStderr);
};