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CompositeHandler.cs
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executable file
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#region License
// The PostgreSQL License
//
// Copyright (C) 2015 The Npgsql Development Team
//
// Permission to use, copy, modify, and distribute this software and its
// documentation for any purpose, without fee, and without a written
// agreement is hereby granted, provided that the above copyright notice
// and this paragraph and the following two paragraphs appear in all copies.
//
// IN NO EVENT SHALL THE NPGSQL DEVELOPMENT TEAM BE LIABLE TO ANY PARTY
// FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES,
// INCLUDING LOST PROFITS, ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS
// DOCUMENTATION, EVEN IF THE NPGSQL DEVELOPMENT TEAM HAS BEEN ADVISED OF
// THE POSSIBILITY OF SUCH DAMAGE.
//
// THE NPGSQL DEVELOPMENT TEAM SPECIFICALLY DISCLAIMS ANY WARRANTIES,
// INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
// AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
// ON AN "AS IS" BASIS, AND THE NPGSQL DEVELOPMENT TEAM HAS NO OBLIGATIONS
// TO PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
#endregion
using System;
using System.Collections.Generic;
using System.Diagnostics.Contracts;
using System.Linq;
using System.Reflection;
using System.Text;
using System.Threading.Tasks;
using Npgsql.BackendMessages;
using NpgsqlTypes;
namespace Npgsql.TypeHandlers
{
/// <summary>
/// Interface implemented by all concrete handlers which handle enums
/// </summary>
internal interface ICompositeHandler
{
/// <summary>
/// The CLR type mapped to the PostgreSQL composite type.
/// </summary>
Type CompositeType { get; }
#pragma warning disable 1591
List<Tuple<string, uint>> RawFields { get; set; }
ICompositeHandler Clone(TypeHandlerRegistry registry);
#pragma warning restore 1591
}
/// <summary>
/// Type handler for PostgreSQL composite types
/// </summary>
/// <remarks>
/// http://www.postgresql.org/docs/current/static/rowtypes.html
///
/// Encoding:
/// A 32-bit integer with the number of columns, then for each column:
/// * An OID indicating the type of the column
/// * The length of the column(32-bit integer), or -1 if null
/// * The column data encoded as binary
/// </remarks>
/// <typeparam name="T">the CLR type to map to the PostgreSQL composite type </typeparam>
internal class CompositeHandler<T> : ChunkingTypeHandler<T>, ICompositeHandler where T : new()
{
readonly TypeHandlerRegistry _registry;
public List<Tuple<string, uint>> RawFields { get; set; }
List<FieldDescriptor> _fields;
NpgsqlBuffer _buf;
LengthCache _lengthCache;
int _fieldIndex;
int _len;
object _value;
bool _wroteFieldHeader;
public Type CompositeType => typeof (T);
internal CompositeHandler() {}
CompositeHandler(TypeHandlerRegistry registry)
{
_registry = registry;
}
#region Read
public override void PrepareRead(NpgsqlBuffer buf, int len, FieldDescription fieldDescription = null)
{
ResolveFieldsIfNeeded();
_buf = buf;
_fieldIndex = -1;
_len = -1;
_value = new T();
}
public override bool Read(out T result)
{
result = default(T);
if (_fieldIndex == -1)
{
if (_buf.ReadBytesLeft < 4) { return false; }
var fieldCount = _buf.ReadInt32();
if (fieldCount != _fields.Count) {
// PostgreSQL sanity check
throw new Exception(
$"pg_attributes contains {_fields.Count} rows for type {PgName}, but {fieldCount} fields were received!");
}
_fieldIndex = 0;
}
for (; _fieldIndex < _fields.Count; _fieldIndex++)
{
var fieldDescriptor = _fields[_fieldIndex];
// Not yet started reading the field.
// Read the type OID (not really needed), then the length.
if (_len == -1)
{
if (_buf.ReadBytesLeft < 8) { return false; }
var typeOID = _buf.ReadInt32();
Contract.Assume(typeOID == fieldDescriptor.Handler.OID);
_len = _buf.ReadInt32();
if (_len == -1)
{
// Null field, simply skip it and leave at default
continue;
}
}
// Get the field's type handler and read the value
var handler = fieldDescriptor.Handler;
object fieldValue = null;
if (handler is ISimpleTypeHandler)
{
var asSimpleReader = (ISimpleTypeHandler)handler;
if (_buf.ReadBytesLeft < _len) { return false; }
fieldValue = asSimpleReader.ReadAsObject(_buf, _len);
}
else if (handler is IChunkingTypeHandler)
{
var asChunkingReader = (IChunkingTypeHandler)handler;
asChunkingReader.PrepareRead(_buf, _len);
if (!asChunkingReader.ReadAsObject(out fieldValue)) {
return false;
}
}
else throw PGUtil.ThrowIfReached();
fieldDescriptor.SetValue(_value, fieldValue);
_len = -1;
}
result = (T)_value;
return true;
}
#endregion
#region Write
public override int ValidateAndGetLength(object value, ref LengthCache lengthCache, NpgsqlParameter parameter)
{
ResolveFieldsIfNeeded();
if (lengthCache == null)
{
lengthCache = new LengthCache(1);
}
if (lengthCache.IsPopulated)
{
return lengthCache.Get();
}
// Leave empty slot for the entire composite type, and go ahead an populate the element slots
var pos = lengthCache.Position;
lengthCache.Set(0);
var totalLen = 4; // number of fields
foreach (var f in _fields)
{
totalLen += 4 + 4; // type oid + field length
var fieldValue = f.GetValue(value);
var asChunkingWriter = f.Handler as IChunkingTypeHandler;
totalLen += asChunkingWriter?.ValidateAndGetLength(fieldValue, ref lengthCache, parameter) ??
((ISimpleTypeHandler)f.Handler).ValidateAndGetLength(fieldValue, null);
}
return lengthCache.Lengths[pos] = totalLen;
}
public override void PrepareWrite(object value, NpgsqlBuffer buf, LengthCache lengthCache, NpgsqlParameter parameter)
{
_value = (T)value;
_buf = buf;
_lengthCache = lengthCache;
_fieldIndex = -1;
_wroteFieldHeader = false;
}
public override bool Write(ref DirectBuffer directBuf)
{
if (_fieldIndex == -1)
{
if (_buf.WriteSpaceLeft < 4) { return false; }
_buf.WriteInt32(_fields.Count);
_fieldIndex = 0;
}
for (; _fieldIndex < _fields.Count; _fieldIndex++)
{
var fieldDescriptor = _fields[_fieldIndex];
var fieldHandler = fieldDescriptor.Handler;
var fieldValue = fieldDescriptor.GetValue(_value);
var asSimpleWriter = fieldHandler as ISimpleTypeHandler;
if (asSimpleWriter != null)
{
var elementLen = asSimpleWriter.ValidateAndGetLength(fieldValue, null);
if (_buf.WriteSpaceLeft < 8 + elementLen) { return false; }
_buf.WriteUInt32(fieldDescriptor.Handler.OID);
_buf.WriteInt32(elementLen);
asSimpleWriter.Write(fieldValue, _buf, null);
continue;
}
var asChunkedWriter = fieldHandler as IChunkingTypeHandler;
if (asChunkedWriter != null)
{
if (!_wroteFieldHeader)
{
if (_buf.WriteSpaceLeft < 8) { return false; }
_buf.WriteUInt32(fieldDescriptor.Handler.OID);
_buf.WriteInt32(asChunkedWriter.ValidateAndGetLength(fieldValue, ref _lengthCache, null));
asChunkedWriter.PrepareWrite(fieldValue, _buf, _lengthCache, null);
_wroteFieldHeader = true;
}
if (!asChunkedWriter.Write(ref directBuf))
{
return false;
}
_wroteFieldHeader = false;
continue;
}
throw PGUtil.ThrowIfReached();
}
return true;
}
#endregion
#region Misc
void ResolveFieldsIfNeeded()
{
if (_fields != null) { return; }
_fields = new List<FieldDescriptor>(RawFields.Count);
foreach (var rawField in RawFields)
{
TypeHandler fieldHandler;
if (!_registry.OIDIndex.TryGetValue(rawField.Item2, out fieldHandler))
{
throw new Exception(
$"PostgreSQL composite type {PgName}, mapped to CLR type {typeof (T).Name}, has field {rawField.Item1} with a type that hasn't been registered (OID={rawField.Item2})");
}
var member = (
from m in typeof (T).GetMembers()
let attr = m.GetCustomAttribute<PgNameAttribute>()
where (attr != null && attr.PgName == rawField.Item1) ||
(attr == null && m.Name == rawField.Item1)
select m
).SingleOrDefault();
if (member == null)
{
throw new Exception(
$"PostgreSQL composite type {PgName} contains field {rawField.Item1} which could not match any on CLR type {typeof (T).Name}");
}
var property = member as PropertyInfo;
if (property != null)
{
_fields.Add(new FieldDescriptor(rawField.Item1, fieldHandler, property));
continue;
}
var field = member as FieldInfo;
if (field != null)
{
_fields.Add(new FieldDescriptor(rawField.Item1, fieldHandler, field));
continue;
}
throw new Exception(
$"PostgreSQL composite type {PgName} contains field {rawField.Item1} which cannot map to CLR type {typeof (T).Name}'s field {member.Name} of type {member.GetType().Name}");
}
RawFields = null;
}
public ICompositeHandler Clone(TypeHandlerRegistry registry)
{
return new CompositeHandler<T>(registry);
}
struct FieldDescriptor
{
internal readonly string Name;
internal readonly TypeHandler Handler;
readonly PropertyInfo _property;
readonly FieldInfo _field;
internal FieldDescriptor(string name, TypeHandler handler, PropertyInfo property)
{
Name = name;
Handler = handler;
_property = property;
_field = null;
}
internal FieldDescriptor(string name, TypeHandler handler, FieldInfo field)
{
Name = name;
Handler = handler;
_property = null;
_field = field;
}
internal void SetValue(object container, object fieldValue)
{
if (_property != null)
{
_property.SetValue(container, fieldValue);
}
else if (_field != null)
{
_field.SetValue(container, fieldValue);
}
else throw PGUtil.ThrowIfReached();
}
internal object GetValue(object container)
{
if (_property != null)
{
return _property.GetValue(container);
}
if (_field != null)
{
return _field.GetValue(container);
}
throw PGUtil.ThrowIfReached();
}
}
#endregion
}
}