jvmMain.io.ktor.util.Deflater.kt Maven / Gradle / Ivy
/*
* Copyright 2014-2021 JetBrains s.r.o and contributors. Use of this source code is governed by the Apache 2.0 license.
*/
package io.ktor.util
import io.ktor.util.cio.*
import io.ktor.utils.io.*
import io.ktor.utils.io.bits.*
import io.ktor.utils.io.pool.*
import kotlinx.coroutines.*
import java.nio.ByteBuffer
import java.util.zip.*
import kotlin.coroutines.*
internal const val GZIP_MAGIC: Short = 0x8b1f.toShort()
internal val GZIP_HEADER_PADDING: ByteArray = ByteArray(7)
private fun Deflater.deflateTo(outBuffer: ByteBuffer) {
if (outBuffer.hasRemaining()) {
val written = deflate(outBuffer.array(), outBuffer.arrayOffset() + outBuffer.position(), outBuffer.remaining())
outBuffer.position(outBuffer.position() + written)
}
}
private fun Deflater.setInputBuffer(buffer: ByteBuffer) {
require(buffer.hasArray()) { "buffer need to be array-backed" }
setInput(buffer.array(), buffer.arrayOffset() + buffer.position(), buffer.remaining())
}
internal fun Checksum.updateKeepPosition(buffer: ByteBuffer) {
require(buffer.hasArray()) { "buffer need to be array-backed" }
update(buffer.array(), buffer.arrayOffset() + buffer.position(), buffer.remaining())
}
private suspend fun ByteWriteChannel.putGzipHeader() {
writeShort(GZIP_MAGIC.reverseByteOrder())
writeByte(Deflater.DEFLATED.toByte())
writeFully(GZIP_HEADER_PADDING)
}
private suspend fun ByteWriteChannel.putGzipTrailer(crc: Checksum, deflater: Deflater) {
writeInt(crc.value.toInt().reverseByteOrder())
writeInt(deflater.totalIn.reverseByteOrder())
}
private suspend fun ByteWriteChannel.deflateWhile(deflater: Deflater, buffer: ByteBuffer, predicate: () -> Boolean) {
while (predicate()) {
buffer.clear()
deflater.deflateTo(buffer)
buffer.flip()
writeFully(buffer)
}
}
/**
* Does deflate compression
* optionally doing CRC and writing GZIP header and trailer if [gzip] = `true`
*/
private suspend fun ByteReadChannel.deflateTo(
destination: ByteWriteChannel,
gzip: Boolean = true,
pool: ObjectPool = KtorDefaultPool
) {
val crc = CRC32()
val deflater = Deflater(Deflater.DEFAULT_COMPRESSION, true)
val input = pool.borrow()
val compressed = pool.borrow()
try {
if (gzip) {
destination.putGzipHeader()
}
while (!isClosedForRead) {
input.clear()
if (readAvailable(input) <= 0) continue
input.flip()
crc.updateKeepPosition(input)
deflater.setInputBuffer(input)
destination.deflateWhile(deflater, compressed) { !deflater.needsInput() }
}
closedCause?.let { throw it }
deflater.finish()
destination.deflateWhile(deflater, compressed) { !deflater.finished() }
if (gzip) {
destination.putGzipTrailer(crc, deflater)
}
} finally {
deflater.end()
pool.recycle(input)
pool.recycle(compressed)
}
}
/**
* Launch a coroutine on [coroutineContext] that does deflate compression
* optionally doing CRC and writing GZIP header and trailer if [gzip] = `true`
*/
@OptIn(DelicateCoroutinesApi::class)
public fun ByteReadChannel.deflated(
gzip: Boolean = true,
pool: ObjectPool = KtorDefaultPool,
coroutineContext: CoroutineContext = Dispatchers.Unconfined
): ByteReadChannel = GlobalScope.writer(coroutineContext, autoFlush = true) {
[email protected](channel, gzip, pool)
}.channel
/**
* Launch a coroutine on [coroutineContext] that does deflate compression
* optionally doing CRC and writing GZIP header and trailer if [gzip] = `true`
*/
@OptIn(DelicateCoroutinesApi::class)
public fun ByteWriteChannel.deflated(
gzip: Boolean = true,
pool: ObjectPool = KtorDefaultPool,
coroutineContext: CoroutineContext = Dispatchers.Unconfined
): ByteWriteChannel = GlobalScope.reader(coroutineContext, autoFlush = true) {
channel.deflateTo(this@deflated, gzip, pool)
}.channel