Class ConnectionHandler (0.20.0)

public class ConnectionHandler extends Thread

Handles a connection from a client to Spanner. This ConnectionHandler uses WireMessage to receive and send all messages from and to the client, using the intermediate representation IntermediateStatement that servers as a middle layer between Postgres and Spanner.

Each ConnectionHandler is also a Thread. Although a TCP connection does not necessarily need to have its own thread, this makes the implementation more straightforward.

Inheritance

java.lang.Object > Thread > ConnectionHandler

Methods

cancelActiveStatement(int connectionId, int secret)

public boolean cancelActiveStatement(int connectionId, int secret)

To be used by a cancellation command to cancel a currently running statement, as contained in a specific connection identified by connectionId. Since cancellation is a flimsy contract at best, it is not imperative that the cancellation run, but it should be attempted nonetheless.

Parameters
NameDescription
connectionIdint

The connection whose statement must be cancelled.

secretint

The secret value linked to the connection that is being cancelled. If it does not match, we cannot cancel.

Returns
TypeDescription
boolean

true if the statement was cancelled.

cleanUp(IntermediateStatement statement)

public void cleanUp(IntermediateStatement statement)

Closes portals and statements if the result of an execute was the end of a transaction.

Parameter
NameDescription
statementIntermediateStatement
Exceptions
TypeDescription
Exception

clearActiveCopyStatement()

public void clearActiveCopyStatement()

clearInvalidMessageCount()

public void clearInvalidMessageCount()

Clears the number of invalid messages that was received. This is called whenever a valid message is encountered.

closeAllStatements()

public void closeAllStatements()

closePortal(String portalName)

public void closePortal(String portalName)
Parameter
NameDescription
portalNameString
Exceptions
TypeDescription
Exception

closeStatement(String statementName)

public void closeStatement(String statementName)
Parameter
NameDescription
statementNameString

connectToSpanner(String database, Credentials credentials)

public void connectToSpanner(String database, Credentials credentials)
Parameters
NameDescription
databaseString
credentialscom.google.auth.Credentials

getActiveCopyStatement()

public CopyStatement getActiveCopyStatement()
Returns
TypeDescription
CopyStatement

getAutoDescribedStatement(String sql)

public Future<DescribeResult> getAutoDescribedStatement(String sql)

Returns the parameter types of a cached auto-described statement, or null if none is available in the cache.

Parameter
NameDescription
sqlString
Returns
TypeDescription
Future<DescribeResult>

getConnectionId()

public int getConnectionId()
Returns
TypeDescription
int

getConnectionMetadata()

public ConnectionMetadata getConnectionMetadata()
Returns
TypeDescription
ConnectionMetadata

getDatabaseId()

public DatabaseId getDatabaseId()
Returns
TypeDescription
com.google.cloud.spanner.DatabaseId

getExtendedQueryProtocolHandler()

public ExtendedQueryProtocolHandler getExtendedQueryProtocolHandler()
Returns
TypeDescription
ExtendedQueryProtocolHandler

getInvalidMessageCount()

public int getInvalidMessageCount()

Returns the number of invalid messages that this connection has received in a row. This can for example happen if a client has initiated a COPY operation and the copy operation fails on the server. The server will then respond with an error response, but if the client fails to read that message and continues to send copy data messages, the server could get flooded. This value is used to detect such a situation and breaks the connection if too many invalid messages in a row are received.

Returns
TypeDescription
int

getPortal(String portalName)

public IntermediatePortalStatement getPortal(String portalName)
Parameter
NameDescription
portalNameString
Returns
TypeDescription
IntermediatePortalStatement

getSecret()

public int getSecret()
Returns
TypeDescription
int

getServer()

public ProxyServer getServer()
Returns
TypeDescription
ProxyServer

getSpannerConnection()

public Connection getSpannerConnection()
Returns
TypeDescription
Connection

getStatement(String statementName)

public IntermediatePreparedStatement getStatement(String statementName)
Parameter
NameDescription
statementNameString
Returns
TypeDescription
IntermediatePreparedStatement

getStatus()

public synchronized ConnectionHandler.ConnectionStatus getStatus()
Returns
TypeDescription
ConnectionHandler.ConnectionStatus

getWellKnownClient()

public ClientAutoDetector.WellKnownClient getWellKnownClient()
Returns
TypeDescription
ClientAutoDetector.WellKnownClient

handleMessages()

public void handleMessages()

Reads and handles wire-protocol messages. This method is normally only called from this ConnectionHandler, but certain sub-protocols such as the COPY protocol also need to process messages in line.

Exceptions
TypeDescription
Exception

handleTerminate()

public void handleTerminate()

Called when a Terminate message is received. This closes this ConnectionHandler.

hasPortal(String portalName)

public boolean hasPortal(String portalName)
Parameter
NameDescription
portalNameString
Returns
TypeDescription
boolean

hasStatement(String statementName)

public boolean hasStatement(String statementName)
Parameter
NameDescription
statementNameString
Returns
TypeDescription
boolean

increaseInvalidMessageCount()

public void increaseInvalidMessageCount()

Increases the number of invalid messages that was received in a row by 1.

maybeDetermineWellKnownClient(Statement statement)

public void maybeDetermineWellKnownClient(Statement statement)

This is called by the simple com.google.cloud.spanner.pgadapter.wireprotocol.QueryMessage to give the connection the opportunity to determine the client that is connected based on the SQL string that is being executed.

Parameter
NameDescription
statementcom.google.cloud.spanner.Statement

maybeDetermineWellKnownClient(ParseMessage parseMessage)

public void maybeDetermineWellKnownClient(ParseMessage parseMessage)

This is called by the extended query protocol com.google.cloud.spanner.pgadapter.wireprotocol.ParseMessage to give the connection the opportunity to determine the client that is connected based on the data in the (first) parse messages.

Parameter
NameDescription
parseMessageParseMessage

registerAutoDescribedStatement(String sql, Future<DescribeResult> describeResult)

public void registerAutoDescribedStatement(String sql, Future<DescribeResult> describeResult)

Stores the parameter types of an auto-described statement in the cache.

Parameters
NameDescription
sqlString
describeResultFuture<DescribeResult>

registerPortal(String portalName, IntermediatePortalStatement portal)

public void registerPortal(String portalName, IntermediatePortalStatement portal)
Parameters
NameDescription
portalNameString
portalIntermediatePortalStatement

registerStatement(String statementName, IntermediatePreparedStatement statement)

public void registerStatement(String statementName, IntermediatePreparedStatement statement)
Parameters
NameDescription
statementNameString
statementIntermediatePreparedStatement

run()

public void run()

Simple runner starts a loop which keeps taking inbound messages, processing them, sending them to Spanner, getting a result, processing that result, and replying to the client (in that order). Also instantiates input and output streams from the client and handles auth.

Overrides

setActiveCopyStatement(CopyStatement copyStatement)

public void setActiveCopyStatement(CopyStatement copyStatement)
Parameter
NameDescription
copyStatementCopyStatement

setMessageState(WireMessage message)

public void setMessageState(WireMessage message)
Parameter
NameDescription
messageWireMessage

setStatus(ConnectionHandler.ConnectionStatus status)

public synchronized void setStatus(ConnectionHandler.ConnectionStatus status)
Parameter
NameDescription
statusConnectionHandler.ConnectionStatus

setWellKnownClient(ClientAutoDetector.WellKnownClient wellKnownClient)

public void setWellKnownClient(ClientAutoDetector.WellKnownClient wellKnownClient)
Parameter
NameDescription
wellKnownClientClientAutoDetector.WellKnownClient