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/*
*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*
*/
#include "WriteEstimate.h"
#include "qpid/log/Statement.h"
#include <boost/current_function.hpp>
namespace qpid {
namespace cluster {
WriteEstimate::WriteEstimate(size_t initial)
: growing(true), estimate(initial) {}
size_t WriteEstimate::sending(size_t buffered) {
// We want to send a doOutput request for enough data such
// that if estimate bytes are written before it is self
// delivered then what is left in the buffer plus the doOutput
// request will be estimate bytes.
size_t predictLeft = (buffered > estimate) ? buffered - estimate : 0;
size_t request = (estimate > predictLeft) ? estimate - predictLeft : 0;
return request;
}
size_t pad(size_t value) { return value + value/2; }
void WriteEstimate::delivered(size_t sent, size_t buffered) {
size_t wrote = sent > buffered ? sent - buffered : 0;
if (wrote == 0) // No change
return;
if (buffered > 0) { // Buffer was over-stocked, we wrote to capacity.
growing = false;
estimate = pad(wrote); // Estimate at 1.5 write for padding.
}
else if (wrote > estimate) { // Wrote everything, buffer was under-stocked
if (growing)
estimate = std::max(estimate*2, pad(wrote)); // Grow quickly if we have not yet seen an over-stock.
else
estimate = pad(wrote);
}
}
}} // namespace qpid::cluster
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