python/benchmarks/io.py

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import time
import pyarrow as pa


class HighLatencyReader(object):

    def __init__(self, raw, latency):
        self.raw = raw
        self.latency = latency

    def close(self):
        self.raw.close()

    @property
    def closed(self):
        return self.raw.closed

    def read(self, nbytes=None):
        time.sleep(self.latency)
        return self.raw.read(nbytes)


class HighLatencyWriter(object):

    def __init__(self, raw, latency):
        self.raw = raw
        self.latency = latency

    def close(self):
        self.raw.close()

    @property
    def closed(self):
        return self.raw.closed

    def write(self, data):
        time.sleep(self.latency)
        self.raw.write(data)


class BufferedIOHighLatency(object):
    """Benchmark creating a parquet manifest."""

    increment = 1024
    total_size = 16 * (1 << 20)  # 16 MB
    buffer_size = 1 << 20  # 1 MB
    latency = 0.1  # 100ms

    param_names = ('latency',)
    params = [0, 0.01, 0.1]

    def time_buffered_writes(self, latency):
        test_data = b'x' * self.increment
        bytes_written = 0
        out = pa.BufferOutputStream()
        slow_out = HighLatencyWriter(out, latency)
        buffered_out = pa.output_stream(slow_out, buffer_size=self.buffer_size)

        while bytes_written < self.total_size:
            buffered_out.write(test_data)
            bytes_written += self.increment
        buffered_out.flush()

    def time_buffered_reads(self, latency):
        bytes_read = 0
        reader = pa.input_stream(pa.py_buffer(b'x' * self.total_size))
        slow_reader = HighLatencyReader(reader, latency)
        buffered_reader = pa.input_stream(slow_reader,
                                          buffer_size=self.buffer_size)
        while bytes_read < self.total_size:
            buffered_reader.read(self.increment)
            bytes_read += self.increment