private NativeToBackendTypeConverterOptions(bool Immutable, bool useConformantStrings, bool supports_E_StringPrefix, bool supportsHexByteFormat, NpgsqlBackendTypeMapping oidToNameMapping)
{
this.IsImmutable = Immutable;
this._UseConformantStrings = useConformantStrings;
this._Supports_E_StringPrefix = supports_E_StringPrefix;
this._SupportsHexByteFormat = supportsHexByteFormat;
this._oidToNameMapping = oidToNameMapping;
}
///<summary>
/// This method creates (or retrieves from cache) a mapping between type and OID
/// of all natively supported postgresql data types.
/// This is needed as from one version to another, this mapping can be changed and
/// so we avoid hardcoding them.
/// </summary>
/// <returns>NpgsqlTypeMapping containing all known data types. The mapping must be
/// cloned before it is modified because it is cached; changes made by one connection may
/// effect another connection.
/// </returns>
public static NpgsqlBackendTypeMapping CreateAndLoadInitialTypesMapping(NpgsqlConnector conn)
{
NpgsqlEventLog.LogMethodEnter(LogLevel.Debug, CLASSNAME, "LoadTypesMapping");
MappingKey key = new MappingKey(conn);
// Check the cache for an initial types map.
NpgsqlBackendTypeMapping oidToNameMapping = null;
if (BackendTypeMappingCache.TryGetValue(key, out oidToNameMapping))
{
return(oidToNameMapping);
}
// Not in cache, create a new one.
oidToNameMapping = new NpgsqlBackendTypeMapping();
// Create a list of all natively supported postgresql data types.
// Attempt to map each type info in the list to an OID on the backend and
// add each mapped type to the new type mapping object.
LoadTypesMappings(conn, oidToNameMapping, TypeInfoList(conn.UseExtendedTypes, conn.CompatVersion));
//We hold the lock for the least time possible on the least scope possible.
//We must lock on BackendTypeMappingCache because it will be updated by this operation,
//and we must not just add to it, but also check that another thread hasn't updated it
//in the meantime. Strictly just doing :
//return BackendTypeMappingCache[key] = oidToNameMapping;
//as the only call within the locked section should be safe and correct, but we'll assume
//there's some subtle problem with temporarily having two copies of the same mapping and
//ensure only one is called.
//It is of course wasteful that multiple threads could be creating mappings when only one
//will be used, but we aim for better overall concurrency at the risk of causing some
//threads the extra work.
NpgsqlBackendTypeMapping mappingCheck = null;
//First check without acquiring the lock; don't lock if we don't have to.
if (BackendTypeMappingCache.TryGetValue(key, out mappingCheck))//Another thread built the mapping in the meantime.
{
return(mappingCheck);
}
lock (BackendTypeMappingCache)
{
//Final check. We have the lock now so if this fails it'll continue to fail.
if (BackendTypeMappingCache.TryGetValue(key, out mappingCheck))//Another thread built the mapping in the meantime.
{
return(mappingCheck);
}
// Add this mapping to the per-server-version cache so we don't have to
// do these expensive queries on every connection startup.
BackendTypeMappingCache.Add(key, oidToNameMapping);
}
return(oidToNameMapping);
}
/// <summary>
/// Attempt to map types by issuing a query against pg_type.
/// This function takes a list of NpgsqlTypeInfo and attempts to resolve the OID field
/// of each by querying pg_type. If the mapping is found, the type info object is
/// updated (OID) and added to the provided NpgsqlTypeMapping object.
/// </summary>
/// <param name="conn">NpgsqlConnector to send query through.</param>
/// <param name="TypeMappings">Mapping object to add types too.</param>
/// <param name="TypeInfoList">List of types that need to have OID's mapped.</param>
public static void LoadTypesMappings(NpgsqlConnector conn, NpgsqlBackendTypeMapping TypeMappings,
IEnumerable <NpgsqlBackendTypeInfo> TypeInfoList)
{
StringBuilder InList = new StringBuilder();
Dictionary <string, NpgsqlBackendTypeInfo> NameIndex = new Dictionary <string, NpgsqlBackendTypeInfo>();
// Build a clause for the SELECT statement.
// Build a name->typeinfo mapping so we can match the results of the query
// with the list of type objects efficiently.
foreach (NpgsqlBackendTypeInfo TypeInfo in TypeInfoList)
{
NameIndex.Add(TypeInfo.Name, TypeInfo);
InList.AppendFormat("{0}'{1}'", ((InList.Length > 0) ? ", " : ""), TypeInfo.Name);
//do the same for the equivalent array type.
NameIndex.Add("_" + TypeInfo.Name, ArrayTypeInfo(TypeInfo));
InList.Append(", '_").Append(TypeInfo.Name).Append('\'');
}
if (InList.Length == 0)
{
return;
}
using (
NpgsqlCommand command =
new NpgsqlCommand(string.Format("SELECT typname, oid FROM pg_type WHERE typname IN ({0})", InList), conn))
{
using (NpgsqlDataReader dr = command.GetReader(CommandBehavior.SequentialAccess | CommandBehavior.SingleResult))
{
while (dr.Read())
{
NpgsqlBackendTypeInfo TypeInfo = NameIndex[dr[0].ToString()];
TypeInfo._OID = Convert.ToInt32(dr[1]);
TypeMappings.AddType(TypeInfo);
}
}
}
}
/// <summary>
/// Copy constuctor.
/// </summary>
private NpgsqlBackendTypeMapping(NpgsqlBackendTypeMapping Other)
{
OIDIndex = new Dictionary <int, NpgsqlBackendTypeInfo>(Other.OIDIndex);
NameIndex = new Dictionary <string, NpgsqlBackendTypeInfo>(Other.NameIndex);
}
/// <summary>
/// Clone the current object with a different OID/Name mapping.
/// </summary>
/// <param name="oidToNameMapping">OID/Name mapping object to use in the new instance.</param>
/// <returns>A new NativeToBackendTypeConverterOptions object.</returns>
internal NativeToBackendTypeConverterOptions Clone(NpgsqlBackendTypeMapping oidToNameMapping = null)
{
return(new NativeToBackendTypeConverterOptions(_UseConformantStrings, _Supports_E_StringPrefix, _SupportsHexByteFormat, oidToNameMapping));
}
internal NativeToBackendTypeConverterOptions(bool useConformantStrings, bool supports_E_StringPrefix, bool supportsHexByteFormat, NpgsqlBackendTypeMapping oidToNameMapping)
: this(false, useConformantStrings, supports_E_StringPrefix, supportsHexByteFormat, oidToNameMapping)
{
}
