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ParseMessage.cs
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executable file
·144 lines (121 loc) · 5 KB
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using System;
using System.Collections.Generic;
using System.Diagnostics.Contracts;
using System.Linq;
using System.Text;
namespace Npgsql.FrontendMessages
{
class ParseMessage : ChunkingFrontendMessage
{
/// <summary>
/// The query string to be parsed.
/// </summary>
string Query { get; set; }
/// <summary>
/// The name of the destination prepared statement (an empty string selects the unnamed prepared statement).
/// </summary>
string Statement { get; set; }
// ReSharper disable once InconsistentNaming
internal List<uint> ParameterTypeOIDs { get; private set; }
byte[] _statementNameBytes;
int _queryLen;
char[] _queryChars;
int _charPos;
State _state;
const byte Code = (byte)'P';
internal ParseMessage()
{
ParameterTypeOIDs = new List<uint>();
}
internal ParseMessage Populate(QueryDetails queryDetails, TypeHandlerRegistry typeHandlerRegistry)
{
_state = State.WroteNothing;
ParameterTypeOIDs.Clear();
Query = queryDetails.Sql;
Statement = queryDetails.PreparedStatementName ?? "";
foreach (var inputParam in queryDetails.InputParameters) {
inputParam.ResolveHandler(typeHandlerRegistry);
ParameterTypeOIDs.Add(inputParam.Handler.OID);
}
return this;
}
internal override bool Write(NpgsqlBuffer buf, ref DirectBuffer directBuf)
{
Contract.Requires(Statement != null && Statement.All(c => c < 128));
switch (_state)
{
case State.WroteNothing:
_statementNameBytes = PGUtil.UTF8Encoding.GetBytes(Statement);
_queryLen = PGUtil.UTF8Encoding.GetByteCount(Query);
if (buf.WriteSpaceLeft < 4 + _statementNameBytes.Length + 1) {
return false;
}
var messageLength =
1 + // Message code
4 + // Length
_statementNameBytes.Length +
1 + // Null terminator
_queryLen +
1 + // Null terminator
2 + // Number of parameters
ParameterTypeOIDs.Count * 4;
buf.WriteByte(Code);
buf.WriteInt32(messageLength - 1);
buf.WriteBytesNullTerminated(_statementNameBytes);
goto case State.WroteHeader;
case State.WroteHeader:
_state = State.WroteHeader;
if (_queryLen <= buf.WriteSpaceLeft) {
buf.WriteStringSimple(Query);
goto case State.WroteQuery;
}
if (_queryLen <= buf.Size) {
// String can fit entirely in an empty buffer. Flush and retry rather than
// going into the partial writing flow below (which requires ToCharArray())
return false;
}
_queryChars = Query.ToCharArray();
_charPos = 0;
goto case State.WritingQuery;
case State.WritingQuery:
_state = State.WritingQuery;
int charsUsed;
bool completed;
buf.WriteStringChunked(_queryChars, _charPos, _queryChars.Length - _charPos, true,
out charsUsed, out completed);
if (!completed)
{
_charPos += charsUsed;
return false;
}
goto case State.WroteQuery;
case State.WroteQuery:
_state = State.WroteQuery;
if (buf.WriteSpaceLeft < 1 + 2 + ParameterTypeOIDs.Count * 4) {
return false;
}
buf.WriteByte(0); // Null terminator for the query
buf.WriteInt16((short)ParameterTypeOIDs.Count);
foreach (var t in ParameterTypeOIDs) {
buf.WriteInt32((int)t);
}
_state = State.WroteAll;
return true;
default:
throw PGUtil.ThrowIfReached();
}
}
public override string ToString()
{
return String.Format("[Parse(Statement={0},NumParams={1}]", Statement, ParameterTypeOIDs.Count);
}
private enum State
{
WroteNothing,
WroteHeader,
WritingQuery,
WroteQuery,
WroteAll
}
}
}