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replicant-frameworks_native/libs/binder/CursorWindow.cpp
Jeff Brown ec4e0063a1 Use ashmem for CursorWindows. 
Bug: 5332296

The memory dealer introduces additional delays for reclaiming
the memory owned by CursorWindows because the Binder object must
be finalized.  Using ashmem instead gives CursorWindow more
direct control over the lifetime of the shared memory region.

The provider now allocates the CursorWindows and returns them
to clients with a read-only protection bit set on the ashmem
region.

Improved the encapsulation of CursorWindow.  Callers shouldn't
need to care about details like how string fields are allocated.

Removed the compile-time configuration of string and numeric
storage modes to remove some dead weight.

Change-Id: I07c2bc2a9c573d7e435dcaecd269d25ea9807acd
2011-10-11 11:03:19 -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, bool localOnly,
CursorWindow** outCursorWindow) {
String8 ashmemName("CursorWindow: ");
ashmemName.append(name);
ashmemName.append(localOnly ? " (local)" : " (remote)");
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) {
LOGE("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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