HandleRangeAllocator.cpp

Branch :

Show log
Commit
Author : Stuart Morgan
Date : 2019-08-14 12:25:12
Hash : 9d737966
Message : Standardize copyright notices to project style For all "ANGLE Project" copyrights, standardize to the format specified by the style guide. Changes: - "Copyright (c)" and "Copyright(c)" changed to just "Copyright". - Removed the second half of date ranges ("Y1Y1-Y2Y2"->"Y1Y1"). - Fixed a small number of files that had no copyright date using the initial commit year from the version control history. - Fixed one instance of copyright being "The ANGLE Project" rather than "The ANGLE Project Authors" These changes are applied both to the copyright of source file, and where applicable to copyright statements that are generated by templates. BUG=angleproject:3811 Change-Id: I973dd65e4ef9deeba232d5be74c768256a0eb2e5 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1754397 Commit-Queue: Jamie Madill <jmadill@chromium.org> Reviewed-by: Jamie Madill <jmadill@chromium.org>

src/libANGLE/HandleRangeAllocator.cpp

//
// Copyright 2016 The ANGLE Project Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
//

// HandleRangeAllocator.cpp : Implementation for HandleRangeAllocator.h

#include "libANGLE/HandleRangeAllocator.h"

#include <algorithm>
#include <limits>
#include <utility>

#include "common/angleutils.h"
#include "common/debug.h"

namespace gl
{

const GLuint HandleRangeAllocator::kInvalidHandle = 0;

HandleRangeAllocator::HandleRangeAllocator()
{
    // Simplify the code by making sure that lower_bound(id) never
    // returns the beginning of the map, if id is valid (eg != kInvalidHandle).
    mUsed.insert(std::make_pair(0u, 0u));
}

HandleRangeAllocator::~HandleRangeAllocator() {}

GLuint HandleRangeAllocator::allocate()
{
    return allocateRange(1u);
}

GLuint HandleRangeAllocator::allocateAtOrAbove(GLuint wanted)
{
    if (wanted == 0u || wanted == 1u)
        return allocateRange(1u);

    auto current = mUsed.lower_bound(wanted);
    auto next    = current;
    if (current == mUsed.end() || current->first > wanted)
    {
        current--;
    }
    else
    {
        next++;
    }

    GLuint firstId = current->first;
    GLuint lastId  = current->second;
    ASSERT(wanted >= firstId);

    if (wanted - 1u <= lastId)
    {
        // Append to current range.
        lastId++;
        if (lastId == 0)
        {
            // The increment overflowed.
            return allocateRange(1u);
        }

        current->second = lastId;

        if (next != mUsed.end() && next->first - 1u == lastId)
        {
            // Merge with next range.
            current->second = next->second;
            mUsed.erase(next);
        }
        return lastId;
    }
    else if (next != mUsed.end() && next->first - 1u == wanted)
    {
        // Prepend to next range.
        GLuint lastExisting = next->second;
        mUsed.erase(next);
        mUsed.insert(std::make_pair(wanted, lastExisting));
        return wanted;
    }
    mUsed.insert(std::make_pair(wanted, wanted));
    return wanted;
}

GLuint HandleRangeAllocator::allocateRange(GLuint range)
{
    ASSERT(range != 0);

    auto current = mUsed.begin();
    auto next    = current;

    while (++next != mUsed.end())
    {
        if (next->first - current->second > range)
            break;
        current = next;
    }
    const GLuint firstId = current->second + 1u;
    const GLuint lastId  = firstId + range - 1u;

    // deal with wraparound
    if (firstId == 0u || lastId < firstId)
        return kInvalidHandle;

    current->second = lastId;

    if (next != mUsed.end() && next->first - 1u == lastId)
    {
        // merge with next range
        current->second = next->second;
        mUsed.erase(next);
    }
    return firstId;
}

bool HandleRangeAllocator::markAsUsed(GLuint handle)
{
    ASSERT(handle);
    auto current = mUsed.lower_bound(handle);
    if (current != mUsed.end() && current->first == handle)
        return false;

    auto next = current;
    --current;

    if (current->second >= handle)
        return false;

    ASSERT(current->first < handle && current->second < handle);

    if (current->second + 1u == handle)
    {
        // Append to current range.
        current->second = handle;
        if (next != mUsed.end() && next->first - 1u == handle)
        {
            // Merge with next range.
            current->second = next->second;
            mUsed.erase(next);
        }
        return true;
    }
    else if (next != mUsed.end() && next->first - 1u == handle)
    {
        // Prepend to next range.
        GLuint lastExisting = next->second;
        mUsed.erase(next);
        mUsed.insert(std::make_pair(handle, lastExisting));
        return true;
    }

    mUsed.insert(std::make_pair(handle, handle));
    return true;
}

void HandleRangeAllocator::release(GLuint handle)
{
    releaseRange(handle, 1u);
}

void HandleRangeAllocator::releaseRange(GLuint first, GLuint range)
{
    if (range == 0u || (first == 0u && range == 1u))
        return;

    if (first == 0u)
    {
        first++;
        range--;
    }

    GLuint last = first + range - 1u;
    if (last < first)
        last = std::numeric_limits<GLuint>::max();

    while (true)
    {
        auto current = mUsed.lower_bound(last);
        if (current == mUsed.end() || current->first > last)
            --current;

        if (current->second < first)
            return;

        if (current->first >= first)
        {
            const GLuint lastExisting = current->second;
            mUsed.erase(current);
            if (last < lastExisting)
            {
                mUsed.insert(std::make_pair(last + 1u, lastExisting));
            }
        }
        else if (current->second <= last)
        {
            current->second = first - 1u;
        }
        else
        {
            ASSERT(current->first < first && current->second > last);
            const GLuint lastExisting = current->second;
            current->second           = first - 1u;
            mUsed.insert(std::make_pair(last + 1u, lastExisting));
        }
    }
}

bool HandleRangeAllocator::isUsed(GLuint handle) const
{
    if (handle == kInvalidHandle)
        return false;

    auto current = mUsed.lower_bound(handle);
    if (current != mUsed.end())
    {
        if (current->first == handle)
            return true;
    }
    --current;
    return current->second >= handle;
}

}  // namespace gl

kc3-lang/angle/src/libANGLE/HandleRangeAllocator.cpp

Commit

kc3-lang/angle /src/libANGLE/HandleRangeAllocator.cpp