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// Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "base/process.h"
#include "base/logging.h"
#include "base/process_util.h"
#include "base/scoped_ptr.h"
namespace base {
void Process::Close() {
if (!process_)
return;
::CloseHandle(process_);
process_ = NULL;
}
void Process::Terminate(int result_code) {
if (!process_)
return;
::TerminateProcess(process_, result_code);
}
bool Process::IsProcessBackgrounded() const {
DCHECK(process_);
DWORD priority = GetPriorityClass(process_);
if (priority == 0)
return false; // Failure case.
return priority == BELOW_NORMAL_PRIORITY_CLASS;
}
bool Process::SetProcessBackgrounded(bool value) {
DCHECK(process_);
DWORD priority = value ? BELOW_NORMAL_PRIORITY_CLASS : NORMAL_PRIORITY_CLASS;
return (SetPriorityClass(process_, priority) != 0);
}
// According to MSDN, these are the default values which XP
// uses to govern working set soft limits.
// http://msdn.microsoft.com/en-us/library/ms686234.aspx
static const int kWinDefaultMinSet = 50 * 4096;
static const int kWinDefaultMaxSet = 345 * 4096;
static const int kDampingFactor = 2;
bool Process::ReduceWorkingSet() {
if (!process_)
return false;
// The idea here is that when we the process' working set has gone
// down, we want to release those pages to the OS quickly. However,
// when it is not going down, we want to be careful not to release
// too much back to the OS, as it could cause additional paging.
// We use a damping function to lessen the working set over time.
// As the process grows/shrinks, this algorithm will lag with
// working set reduction.
//
// The intended algorithm is:
// TargetWorkingSetSize = (LastWorkingSet/2 + CurrentWorkingSet) /2
scoped_ptr<ProcessMetrics> metrics(
ProcessMetrics::CreateProcessMetrics(process_));
WorkingSetKBytes working_set;
if (!metrics->GetWorkingSetKBytes(&working_set))
return false;
// We want to compute the amount of working set that the process
// needs to keep in memory. Since other processes contain the
// pages which are shared, we don't need to reserve them in our
// process, the system already has them tagged. Keep in mind, we
// don't get to control *which* pages get released, but if we
// assume reasonable distribution of pages, this should generally
// be the right value.
size_t current_working_set_size = working_set.priv +
working_set.shareable;
size_t max_size = current_working_set_size;
if (last_working_set_size_)
max_size = (max_size + last_working_set_size_) / 2; // Average.
max_size *= 1024; // Convert to KBytes.
last_working_set_size_ = current_working_set_size / kDampingFactor;
BOOL rv = SetProcessWorkingSetSize(process_, kWinDefaultMinSet, max_size);
return rv == TRUE;
}
bool Process::UnReduceWorkingSet() {
if (!process_)
return false;
if (!last_working_set_size_)
return true; // There was nothing to undo.
// We've had a reduced working set. Make sure we have lots of
// headroom now that we're active again.
size_t limit = last_working_set_size_ * kDampingFactor * 2 * 1024;
BOOL rv = SetProcessWorkingSetSize(process_, kWinDefaultMinSet, limit);
return rv == TRUE;
}
bool Process::EmptyWorkingSet() {
if (!process_)
return false;
BOOL rv = SetProcessWorkingSetSize(process_, -1, -1);
return rv == TRUE;
}
int32 Process::pid() const {
if (process_ == 0)
return 0;
return GetProcId(process_);
}
bool Process::is_current() const {
return process_ == GetCurrentProcess();
}
// static
Process Process::Current() {
return Process(GetCurrentProcess());
}
} // namespace base
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