public DryadLinqVertexWriter(VertexEnv denv, DryadLinqFactory <T> writerFactory, UInt32 portNum)
{
this.m_dvertexEnv = denv;
this.m_nativeHandle = denv.NativeHandle;
this.m_startPort = portNum;
this.m_numberOfOutputs = 1;
this.m_writerFactory = writerFactory;
Int32 buffSize = this.m_dvertexEnv.GetWriteBuffSize();
DryadLinqRecordWriter <T> writer = writerFactory.MakeWriter(this.m_nativeHandle, portNum, buffSize);
this.m_writers = new DryadLinqRecordWriter <T>[] { writer };
}
public DryadLinqVertexReader(VertexEnv denv, DryadLinqFactory <T> readerFactory, UInt32 portNum)
{
this.m_dvertexEnv = denv;
this.m_nativeHandle = denv.NativeHandle;
this.m_readerFactory = readerFactory;
this.m_startPort = portNum;
this.m_numberOfInputs = 1;
this.m_keepInputPortOrder = false;
this.m_portPermArray = new UInt32[] { 0 };
DryadLinqRecordReader <T> reader = readerFactory.MakeReader(this.m_nativeHandle, portNum);
this.m_readers = new DryadLinqRecordReader <T>[] { reader };
this.m_isUsed = false;
}
public DryadLinqVertexWriter(VertexEnv denv, DryadLinqFactory <T> writerFactory, UInt32 startPort, UInt32 endPort)
{
this.m_dvertexEnv = denv;
this.m_nativeHandle = denv.NativeHandle;
this.m_startPort = startPort;
this.m_numberOfOutputs = endPort - startPort;
this.m_writerFactory = writerFactory;
this.m_writers = new DryadLinqRecordWriter <T> [this.m_numberOfOutputs];
Int32 buffSize = this.m_dvertexEnv.GetWriteBuffSize();
for (UInt32 i = 0; i < this.m_numberOfOutputs; i++)
{
this.m_writers[i] = writerFactory.MakeWriter(this.m_nativeHandle, i + startPort, buffSize);
}
}
public DryadLinqVertexReader(VertexEnv denv,
DryadLinqFactory <T> readerFactory,
UInt32 startPort,
UInt32 endPort,
bool keepInputPortOrder)
{
this.m_dvertexEnv = denv;
this.m_nativeHandle = denv.NativeHandle;
this.m_readerFactory = readerFactory;
this.m_startPort = startPort;
this.m_numberOfInputs = endPort - startPort;
this.m_keepInputPortOrder = keepInputPortOrder;
this.m_portPermArray = new UInt32[this.NumberOfInputs];
for (UInt32 i = 0; i < this.NumberOfInputs; i++)
{
this.m_portPermArray[i] = i;
}
if (!keepInputPortOrder)
{
Random rdm = new Random(System.Diagnostics.Process.GetCurrentProcess().Id);
Int32 max = (Int32)this.NumberOfInputs;
for (UInt32 i = 1; i < this.NumberOfInputs; i++)
{
int idx = rdm.Next(max);
UInt32 n = this.m_portPermArray[max - 1];
this.m_portPermArray[max - 1] = this.m_portPermArray[idx];
this.m_portPermArray[idx] = n;
max--;
}
}
this.m_readers = new DryadLinqRecordReader <T> [this.NumberOfInputs];
for (UInt32 i = 0; i < this.NumberOfInputs; i++)
{
this.m_readers[i] = this.m_readerFactory.MakeReader(this.m_nativeHandle, startPort + i);
}
this.m_isUsed = false;
}
public static IEnumerable<K> Phase1Sampling<T, K>(IEnumerable<T> source,
Func<T, K> keySelector,
VertexEnv denv)
{
// note: vertexID is constant for each repetition of a specific vertex (eg in fail-and-retry scenarios)
// this is very good as it ensure the sampling is idempotent w.r.t. retries.
long vertexID = DryadLinqNative.GetVertexId(denv.NativeHandle);
int seed = unchecked((int)(vertexID));
long nEmitted = 0;
Random rdm = new Random(seed);
List<K> allSoFar = new List<K>();
List<K> samples = new List<K>();
// try to collect 10 samples, but keep all the records just in case
IEnumerator<T> sourceEnumerator = source.GetEnumerator();
while (sourceEnumerator.MoveNext())
{
T elem = sourceEnumerator.Current;
K key = keySelector(elem);
allSoFar.Add(key);
if (rdm.NextDouble() < SAMPLE_RATE)
{
samples.Add(key);
if (samples.Count >= 10)
break;
}
}
if (samples.Count >= 10)
{
// we have lots of samples.. emit them and continue sampling
allSoFar = null; // not needed.
foreach (K key in samples)
{
yield return key;
nEmitted++;
}
while (sourceEnumerator.MoveNext())
{
T elem = sourceEnumerator.Current;
if (rdm.NextDouble() < SAMPLE_RATE)
{
yield return keySelector(elem);
nEmitted++;
}
}
}
else
{
// sampling didn't produce much, so emit all the records instead.
DryadLinqLog.AddInfo("Sampling produced only {0} records. Emitting all records instead.", samples.Count());
Debug.Assert(sourceEnumerator.MoveNext() == false, "The source enumerator wasn't finished");
samples = null; // the samples list is not needed.
foreach (K key in allSoFar)
{
yield return key;
nEmitted++;
}
}
DryadLinqLog.AddInfo("Stage1 sampling: num keys emitted = {0}", nEmitted);
}
