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// connection mixins// implementation of http://dev.mysql.com/doc/internals/en/compression.html
import {  zlib,  Buffer,  seq_queue as seqqueue,} from "../deps.ts";import { Packet } from "./packets/packet.ts";import { PacketParser } from "./packet_parser.ts";
// deno-lint-ignore no-explicit-anyfunction handleCompressedPacket(_this: any, packet: Packet) {  // deno-lint-ignore no-explicit-any  const connection: any = _this;  const deflatedLength = packet.readInt24();  const body = packet.readBuffer();
  if (deflatedLength !== 0) {    // deno-lint-ignore no-explicit-any    connection.inflateQueue.push((task: any) => {      zlib.inflate(body, (err: Error, data: Buffer) => {        if (err) {          connection._handleNetworkError(err);          return;        }        connection._bumpCompressedSequenceId(packet.numPackets);        connection._inflatedPacketsParser.execute(data);        task.done();      });    });  } else {    // deno-lint-ignore no-explicit-any    connection.inflateQueue.push((task: any) => {      connection._bumpCompressedSequenceId(packet.numPackets);      connection._inflatedPacketsParser.execute(body);      task.done();    });  }}
// deno-lint-ignore no-explicit-anyfunction writeCompressed(this: any, buffer: Buffer) {  // http://dev.mysql.com/doc/internals/en/example-several-mysql-packets.html  // note: sending a MySQL Packet of the size 2^24−5 to 2^24−1 via compression  // leads to at least one extra compressed packet.  // (this is because "length of the packet before compression" need to fit  // into 3 byte unsigned int. "length of the packet before compression" includes  // 4 byte packet header, hence 2^24−5)  const MAX_COMPRESSED_LENGTH = 16777210;  let start;  if (buffer.length > MAX_COMPRESSED_LENGTH) {    for (start = 0; start < buffer.length; start += MAX_COMPRESSED_LENGTH) {      writeCompressed.call(        // deno-lint-ignore no-explicit-any        this as any,        buffer.slice(start, start + MAX_COMPRESSED_LENGTH)      );    }    return;  }
  // eslint-disable-next-line no-invalid-this, consistent-this no-this-alias  // deno-lint-ignore no-explicit-any  const connection = <any> this;
  let packetLen = buffer.length;  const compressHeader = Buffer.allocUnsafe(7);
  // seqqueue is used here because zlib async execution is routed via thread pool  // internally and when we have multiple compressed packets arriving we need  // to assemble uncompressed result sequentially  (function(seqId) {    // deno-lint-ignore no-explicit-any    connection.deflateQueue.push((task: any) => {      zlib.deflate(buffer, (err: Error, compressed: Buffer) => {        if (err) {          connection._handleFatalError(err);          return;        }        let compressedLength = compressed.length;
        if (compressedLength < packetLen) {          compressHeader.writeUInt8(compressedLength & 0xff, 0);          compressHeader.writeUInt16LE(compressedLength >> 8, 1);          compressHeader.writeUInt8(seqId, 3);          compressHeader.writeUInt8(packetLen & 0xff, 4);          compressHeader.writeUInt16LE(packetLen >> 8, 5);          connection.writeUncompressed(compressHeader);          connection.writeUncompressed(compressed);        } else {          // http://dev.mysql.com/doc/internals/en/uncompressed-payload.html          // To send an uncompressed payload:          //   - set length of payload before compression to 0          //   - the compressed payload contains the uncompressed payload instead.          compressedLength = packetLen;          packetLen = 0;          compressHeader.writeUInt8(compressedLength & 0xff, 0);          compressHeader.writeUInt16LE(compressedLength >> 8, 1);          compressHeader.writeUInt8(seqId, 3);          compressHeader.writeUInt8(packetLen & 0xff, 4);          compressHeader.writeUInt16LE(packetLen >> 8, 5);          connection.writeUncompressed(compressHeader);          connection.writeUncompressed(buffer);        }        task.done();      });    });  })(connection.compressedSequenceId);  connection._bumpCompressedSequenceId(1);}
// deno-lint-ignore no-explicit-anyfunction enableCompression(connection: any) {  connection._lastWrittenPacketId = 0;  connection._lastReceivedPacketId = 0;
  // deno-lint-ignore no-explicit-any  connection._handleCompressedPacket = function(...args: any[]) {    args.unshift(this);    // deno-lint-ignore no-explicit-any    return handleCompressedPacket.apply(this, args as any);  };  connection._inflatedPacketsParser = new PacketParser((p) => {    connection.handlePacket(p);  }, 4);  connection._inflatedPacketsParser._lastPacket = 0;  connection.packetParser = new PacketParser((packet) => {    connection._handleCompressedPacket(packet);  }, 7);
  connection.writeUncompressed = connection.write;  connection.write = writeCompressed;
  connection.inflateQueue = seqqueue.createQueue();  connection.deflateQueue = seqqueue.createQueue();}
export {  enableCompression,};