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.
Methods
public synchronized void addActiveStatement(IntermediateStatement statement)
Add a currently executing statement to a buffer. This is only used in case a statement in
flight is cancelled. It must be saved separately, as a new connection is spawned to issue a
cancellation (as per Postgres protocol standard). This means some sort of IPC is required,
which in this case is a global Map.
cancelActiveStatement(int connectionId, int secret)
public synchronized void 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.
| Name | Description |
| connectionId | int
The connection owhose statement must be cancelled.
|
| secret | int
The secret value linked to this connection. If it does not match, we cannot
cancel.
|
public void cleanUp(IntermediateStatement statement)
Closes portals and statements if the result of an execute was the end of a transaction.
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
| Name | Description |
| portalName | String
|
Exceptions
closeStatement(String statementName)
public void closeStatement(String statementName)
Parameter
| Name | Description |
| statementName | String
|
connectToSpanner(String database, GoogleCredentials credentials)
public void connectToSpanner(String database, GoogleCredentials credentials)
Parameters
| Name | Description |
| database | String
|
| credentials | com.google.auth.oauth2.GoogleCredentials
|
getActiveStatement()
public synchronized IntermediateStatement getActiveStatement()
Returns
getConnectionId()
public int getConnectionId()
Returns
public ConnectionMetadata getConnectionMetadata()
Returns
getDatabaseId()
public DatabaseId getDatabaseId()
Returns
| Type | Description |
| com.google.cloud.spanner.DatabaseId | |
getExtendedQueryProtocolHandler()
public ExtendedQueryProtocolHandler getExtendedQueryProtocolHandler()
Returns
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.
getPortal(String portalName)
public IntermediatePortalStatement getPortal(String portalName)
Parameter
| Name | Description |
| portalName | String
|
Returns
getSecret()
Returns
getServer()
public ProxyServer getServer()
Returns
getSpannerConnection()
public Connection getSpannerConnection()
Returns
getStatement(String statementName)
public IntermediatePreparedStatement getStatement(String statementName)
Parameter
| Name | Description |
| statementName | String
|
Returns
getStatus()
public synchronized ConnectionHandler.ConnectionStatus getStatus()
Returns
getWellKnownClient()
public ClientAutoDetector.WellKnownClient getWellKnownClient()
Returns
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.
handleTerminate()
public void handleTerminate()
hasPortal(String portalName)
public boolean hasPortal(String portalName)
Parameter
| Name | Description |
| portalName | String
|
Returns
hasStatement(String statementName)
public boolean hasStatement(String statementName)
Parameter
| Name | Description |
| statementName | String
|
Returns
increaseInvalidMessageCount()
public void increaseInvalidMessageCount()
Increases the number of invalid messages that was received in a row by 1.
public void registerPortal(String portalName, IntermediatePortalStatement portal)
Parameters
public void registerStatement(String statementName, IntermediatePreparedStatement statement)
Parameters
public synchronized void removeActiveStatement(IntermediateStatement statement)
Remove a statement from the buffer if it is currently executing. For more information on this
use-case, read addActiveStatement comment.
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.
setMessageState(WireMessage message)
public void setMessageState(WireMessage message)
Parameter
setStatus(ConnectionHandler.ConnectionStatus status)
public synchronized void setStatus(ConnectionHandler.ConnectionStatus status)
Parameter
setWellKnownClient(ClientAutoDetector.WellKnownClient wellKnownClient)
public void setWellKnownClient(ClientAutoDetector.WellKnownClient wellKnownClient)
Parameter
