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replicant-frameworks_native/libs/binder/CursorWindow.cpp
Jeff Brown 20b3da9a01 Optimize fillWindow to improve reverse-seek performance. 
Bug: 5520301

When an application requests a row from a SQLiteCursor that
is not in the window, instead of filling from the requested
row position onwards, fill from a little bit ahead of the
requested row position.

This fixes a problem with applications that seek backwards
in large cursor windows.  Previously the application could
end up refilling the window every time it moved back
one position.

We try to fill about 1/3 before the requested position and
2/3 after which substantially improves scrolling responsiveness
when the list is bound to a data set that does not fit
entirely within one cursor window.

Change-Id: I168ff1d3aed1a41ac96267be34a026c108590e52
2011-10-28 01:46:18 -07:00

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/*
* Copyright (C) 2006-2007 The Android Open Source Project
*
* Licensed 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.
*/
#undef LOG_TAG
#define LOG_TAG "CursorWindow"
#include <utils/Log.h>
#include <binder/CursorWindow.h>
#include <cutils/ashmem.h>
#include <sys/mman.h>
#include <assert.h>
#include <string.h>
#include <stdlib.h>
namespace android {
CursorWindow::CursorWindow(const String8& name, int ashmemFd,
void* data, size_t size, bool readOnly) :
mName(name), mAshmemFd(ashmemFd), mData(data), mSize(size), mReadOnly(readOnly) {
mHeader = static_cast<Header*>(mData);
}
CursorWindow::~CursorWindow() {
::munmap(mData, mSize);
::close(mAshmemFd);
}
status_t CursorWindow::create(const String8& name, size_t size, CursorWindow** outCursorWindow) {
String8 ashmemName("CursorWindow: ");
ashmemName.append(name);
status_t result;
int ashmemFd = ashmem_create_region(ashmemName.string(), size);
if (ashmemFd < 0) {
result = -errno;
} else {
result = ashmem_set_prot_region(ashmemFd, PROT_READ | PROT_WRITE);
if (result >= 0) {
void* data = ::mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, ashmemFd, 0);
if (data == MAP_FAILED) {
result = -errno;
} else {
result = ashmem_set_prot_region(ashmemFd, PROT_READ);
if (result >= 0) {
CursorWindow* window = new CursorWindow(name, ashmemFd,
data, size, false /*readOnly*/);
result = window->clear();
if (!result) {
LOG_WINDOW("Created new CursorWindow: freeOffset=%d, "
"numRows=%d, numColumns=%d, mSize=%d, mData=%p",
window->mHeader->freeOffset,
window->mHeader->numRows,
window->mHeader->numColumns,
window->mSize, window->mData);
*outCursorWindow = window;
return OK;
}
delete window;
}
}
::munmap(data, size);
}
::close(ashmemFd);
}
*outCursorWindow = NULL;
return result;
}
status_t CursorWindow::createFromParcel(Parcel* parcel, CursorWindow** outCursorWindow) {
String8 name = parcel->readString8();
status_t result;
int ashmemFd = parcel->readFileDescriptor();
if (ashmemFd == int(BAD_TYPE)) {
result = BAD_TYPE;
} else {
ssize_t size = ashmem_get_size_region(ashmemFd);
if (size < 0) {
result = UNKNOWN_ERROR;
} else {
int dupAshmemFd = ::dup(ashmemFd);
if (dupAshmemFd < 0) {
result = -errno;
} else {
void* data = ::mmap(NULL, size, PROT_READ, MAP_SHARED, dupAshmemFd, 0);
if (data == MAP_FAILED) {
result = -errno;
} else {
CursorWindow* window = new CursorWindow(name, dupAshmemFd,
data, size, true /*readOnly*/);
LOG_WINDOW("Created CursorWindow from parcel: freeOffset=%d, "
"numRows=%d, numColumns=%d, mSize=%d, mData=%p",
window->mHeader->freeOffset,
window->mHeader->numRows,
window->mHeader->numColumns,
window->mSize, window->mData);
*outCursorWindow = window;
return OK;
}
::close(dupAshmemFd);
}
}
}
*outCursorWindow = NULL;
return result;
}
status_t CursorWindow::writeToParcel(Parcel* parcel) {
status_t status = parcel->writeString8(mName);
if (!status) {
status = parcel->writeDupFileDescriptor(mAshmemFd);
}
return status;
}
status_t CursorWindow::clear() {
if (mReadOnly) {
return INVALID_OPERATION;
}
mHeader->freeOffset = sizeof(Header) + sizeof(RowSlotChunk);
mHeader->firstChunkOffset = sizeof(Header);
mHeader->numRows = 0;
mHeader->numColumns = 0;
RowSlotChunk* firstChunk = static_cast<RowSlotChunk*>(offsetToPtr(mHeader->firstChunkOffset));
firstChunk->nextChunkOffset = 0;
return OK;
}
status_t CursorWindow::setNumColumns(uint32_t numColumns) {
if (mReadOnly) {
return INVALID_OPERATION;
}
uint32_t cur = mHeader->numColumns;
if ((cur > 0 || mHeader->numRows > 0) && cur != numColumns) {
LOGE("Trying to go from %d columns to %d", cur, numColumns);
return INVALID_OPERATION;
}
mHeader->numColumns = numColumns;
return OK;
}
status_t CursorWindow::allocRow() {
if (mReadOnly) {
return INVALID_OPERATION;
}
// Fill in the row slot
RowSlot* rowSlot = allocRowSlot();
if (rowSlot == NULL) {
return NO_MEMORY;
}
// Allocate the slots for the field directory
size_t fieldDirSize = mHeader->numColumns * sizeof(FieldSlot);
uint32_t fieldDirOffset = alloc(fieldDirSize, true /*aligned*/);
if (!fieldDirOffset) {
mHeader->numRows--;
LOG_WINDOW("The row failed, so back out the new row accounting "
"from allocRowSlot %d", mHeader->numRows);
return NO_MEMORY;
}
FieldSlot* fieldDir = static_cast<FieldSlot*>(offsetToPtr(fieldDirOffset));
memset(fieldDir, 0, fieldDirSize);
LOG_WINDOW("Allocated row %u, rowSlot is at offset %u, fieldDir is %d bytes at offset %u\n",
mHeader->numRows - 1, offsetFromPtr(rowSlot), fieldDirSize, fieldDirOffset);
rowSlot->offset = fieldDirOffset;
return OK;
}
status_t CursorWindow::freeLastRow() {
if (mReadOnly) {
return INVALID_OPERATION;
}
if (mHeader->numRows > 0) {
mHeader->numRows--;
}
return OK;
}
uint32_t CursorWindow::alloc(size_t size, bool aligned) {
uint32_t padding;
if (aligned) {
// 4 byte alignment
padding = (~mHeader->freeOffset + 1) & 3;
} else {
padding = 0;
}
uint32_t offset = mHeader->freeOffset + padding;
uint32_t nextFreeOffset = offset + size;
if (nextFreeOffset > mSize) {
LOGW("Window is full: requested allocation %d bytes, "
"free space %d bytes, window size %d bytes",
size, freeSpace(), mSize);
return 0;
}
mHeader->freeOffset = nextFreeOffset;
return offset;
}
CursorWindow::RowSlot* CursorWindow::getRowSlot(uint32_t row) {
uint32_t chunkPos = row;
RowSlotChunk* chunk = static_cast<RowSlotChunk*>(
offsetToPtr(mHeader->firstChunkOffset));
while (chunkPos >= ROW_SLOT_CHUNK_NUM_ROWS) {
chunk = static_cast<RowSlotChunk*>(offsetToPtr(chunk->nextChunkOffset));
chunkPos -= ROW_SLOT_CHUNK_NUM_ROWS;
}
return &chunk->slots[chunkPos];
}
CursorWindow::RowSlot* CursorWindow::allocRowSlot() {
uint32_t chunkPos = mHeader->numRows;
RowSlotChunk* chunk = static_cast<RowSlotChunk*>(
offsetToPtr(mHeader->firstChunkOffset));
while (chunkPos > ROW_SLOT_CHUNK_NUM_ROWS) {
chunk = static_cast<RowSlotChunk*>(offsetToPtr(chunk->nextChunkOffset));
chunkPos -= ROW_SLOT_CHUNK_NUM_ROWS;
}
if (chunkPos == ROW_SLOT_CHUNK_NUM_ROWS) {
if (!chunk->nextChunkOffset) {
chunk->nextChunkOffset = alloc(sizeof(RowSlotChunk), true /*aligned*/);
if (!chunk->nextChunkOffset) {
return NULL;
}
}
chunk = static_cast<RowSlotChunk*>(offsetToPtr(chunk->nextChunkOffset));
chunk->nextChunkOffset = 0;
chunkPos = 0;
}
mHeader->numRows += 1;
return &chunk->slots[chunkPos];
}
CursorWindow::FieldSlot* CursorWindow::getFieldSlot(uint32_t row, uint32_t column) {
if (row >= mHeader->numRows || column >= mHeader->numColumns) {
LOGE("Failed to read row %d, column %d from a CursorWindow which "
"has %d rows, %d columns.",
row, column, mHeader->numRows, mHeader->numColumns);
return NULL;
}
RowSlot* rowSlot = getRowSlot(row);
if (!rowSlot) {
LOGE("Failed to find rowSlot for row %d.", row);
return NULL;
}
FieldSlot* fieldDir = static_cast<FieldSlot*>(offsetToPtr(rowSlot->offset));
return &fieldDir[column];
}
status_t CursorWindow::putBlob(uint32_t row, uint32_t column, const void* value, size_t size) {
return putBlobOrString(row, column, value, size, FIELD_TYPE_BLOB);
}
status_t CursorWindow::putString(uint32_t row, uint32_t column, const char* value,
size_t sizeIncludingNull) {
return putBlobOrString(row, column, value, sizeIncludingNull, FIELD_TYPE_STRING);
}
status_t CursorWindow::putBlobOrString(uint32_t row, uint32_t column,
const void* value, size_t size, int32_t type) {
if (mReadOnly) {
return INVALID_OPERATION;
}
FieldSlot* fieldSlot = getFieldSlot(row, column);
if (!fieldSlot) {
return BAD_VALUE;
}
uint32_t offset = alloc(size);
if (!offset) {
return NO_MEMORY;
}
memcpy(offsetToPtr(offset), value, size);
fieldSlot->type = type;
fieldSlot->data.buffer.offset = offset;
fieldSlot->data.buffer.size = size;
return OK;
}
status_t CursorWindow::putLong(uint32_t row, uint32_t column, int64_t value) {
if (mReadOnly) {
return INVALID_OPERATION;
}
FieldSlot* fieldSlot = getFieldSlot(row, column);
if (!fieldSlot) {
return BAD_VALUE;
}
fieldSlot->type = FIELD_TYPE_INTEGER;
fieldSlot->data.l = value;
return OK;
}
status_t CursorWindow::putDouble(uint32_t row, uint32_t column, double value) {
if (mReadOnly) {
return INVALID_OPERATION;
}
FieldSlot* fieldSlot = getFieldSlot(row, column);
if (!fieldSlot) {
return BAD_VALUE;
}
fieldSlot->type = FIELD_TYPE_FLOAT;
fieldSlot->data.d = value;
return OK;
}
status_t CursorWindow::putNull(uint32_t row, uint32_t column) {
if (mReadOnly) {
return INVALID_OPERATION;
}
FieldSlot* fieldSlot = getFieldSlot(row, column);
if (!fieldSlot) {
return BAD_VALUE;
}
fieldSlot->type = FIELD_TYPE_NULL;
fieldSlot->data.buffer.offset = 0;
fieldSlot->data.buffer.size = 0;
return OK;
}
}; // namespace android
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