org.apache.cassandra.service

Class ClientState

java.lang.Object

org.apache.cassandra.service.ClientState

Direct Known Subclasses:

ThriftClientState

public class ClientState
extends java.lang.Object

State related to a client connection.

Field Summary

Fields

Modifier and Type	Field and Description
static CassandraVersion	DEFAULT_CQL_VERSION
boolean	isInternal

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	ClientState(java.net.InetSocketAddress remoteAddress)

Method Summary

Modifier and Type	Method and Description
void	ensureHasPermission(Permission permission, Function function)
void	ensureHasPermission(Permission perm, IResource resource)
void	ensureIsSuper(java.lang.String message)
void	ensureNotAnonymous()
static ClientState	forExternalCalls(java.net.SocketAddress remoteAddress)
static ClientState	forInternalCalls()
static QueryHandler	getCQLQueryHandler()
static CassandraVersion[]	getCQLSupportedVersion()
java.lang.String	getKeyspace()
java.lang.String	getRawKeyspace()
java.net.InetSocketAddress	getRemoteAddress()
long	getTimestamp() This clock guarantees that updates for the same ClientState will be ordered in the sequence seen, even if multiple updates happen in the same millisecond.
long	getTimestampForPaxos(long minTimestampToUse) Returns a timestamp suitable for paxos given the timestamp of the last known commit (or in progress update).
AuthenticatedUser	getUser()
void	hasAllKeyspacesAccess(Permission perm)
void	hasColumnFamilyAccess(CFMetaData cfm, Permission perm)
void	hasColumnFamilyAccess(java.lang.String keyspace, java.lang.String columnFamily, Permission perm)
void	hasKeyspaceAccess(java.lang.String keyspace, Permission perm)
boolean	isNoCompactMode()
void	login(AuthenticatedUser user) Attempts to login the given user.
void	setKeyspace(java.lang.String ks)
void	setNoCompactMode()
void	validateLogin()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

DEFAULT_CQL_VERSION

public static final CassandraVersion DEFAULT_CQL_VERSION

isInternal

public final boolean isInternal

Constructor Detail

ClientState

protected ClientState(java.net.InetSocketAddress remoteAddress)

Method Detail

forInternalCalls

public static ClientState forInternalCalls()

Returns:

a ClientState object for internal C* calls (not limited by any kind of auth).

forExternalCalls

public static ClientState forExternalCalls(java.net.SocketAddress remoteAddress)

Returns:

a ClientState object for external clients (thrift/native protocol users).

getTimestamp

public long getTimestamp()

This clock guarantees that updates for the same ClientState will be ordered in the sequence seen, even if multiple updates happen in the same millisecond.

getTimestampForPaxos

public long getTimestampForPaxos(long minTimestampToUse)

Returns a timestamp suitable for paxos given the timestamp of the last known commit (or in progress update).

Paxos ensures that the timestamp it uses for commits respects the serial order of those commits. It does so by having each replica reject any proposal whose timestamp is not strictly greater than the last proposal it accepted. So in practice, which timestamp we use for a given proposal doesn't affect correctness but it does affect the chance of making progress (if we pick a timestamp lower than what has been proposed before, our new proposal will just get rejected).

As during the prepared phase replica send us the last propose they accepted, a first option would be to take the maximum of those last accepted proposal timestamp plus 1 (and use a default value, say 0, if it's the first known proposal for the partition). This would most work (giving commits the timestamp 0, 1, 2, ... in the order they are commited) up to 2 important caveats: 1) it would give a very poor experience when Paxos and non-Paxos updates are mixed in the same partition, since paxos operations wouldn't be using microseconds timestamps. And while you shouldn't theoretically mix the 2 kind of operations, this would still be pretty unintuitive. And what if you started writing normal updates and realize later you should switch to Paxos to enforce a property you want? 2) this wouldn't actually be safe due to the expiration set on the Paxos state table.

So instead, we initially chose to use the current time in microseconds as for normal update. Which works in general but mean that clock skew creates unavailability periods for Paxos updates (either a node has his clock in the past and he may no be able to get commit accepted until its clock catch up, or a node has his clock in the future and then once one of its commit his accepted, other nodes ones won't be until they catch up). This is ok for small clock skew (few ms) but can be pretty bad for large one.

Hence our current solution: we mix both approaches. That is, we compare the timestamp of the last known accepted proposal and the local time. If the local time is greater, we use it, thus keeping paxos timestamps locked to the current time in general (making mixing Paxos and non-Paxos more friendly, and behaving correctly when the paxos state expire (as long as your maximum clock skew is lower than the Paxos state expiration time)). Otherwise (the local time is lower than the last proposal, meaning that this last proposal was done with a clock in the future compared to the local one), we use the last proposal timestamp plus 1, ensuring progress.

Parameters:

minTimestampToUse - the max timestamp of the last proposal accepted by replica having responded to the prepare phase of the paxos round this is for. In practice, that's the minimum timestamp this method may return.

Returns:

a timestamp suitable for a Paxos proposal (using the reasoning described above). Note that contrarily to the getTimestamp() method, the return value is not guaranteed to be unique (nor monotonic) across calls since it can return it's argument (so if the same argument is passed multiple times, it may be returned multiple times). Note that we still ensure Paxos "ballot" are unique (for different proposal) by (securely) randomizing the non-timestamp part of the UUID.

getCQLQueryHandler

public static QueryHandler getCQLQueryHandler()

getRemoteAddress

public java.net.InetSocketAddress getRemoteAddress()

getRawKeyspace

public java.lang.String getRawKeyspace()

getKeyspace

public java.lang.String getKeyspace()
                             throws InvalidRequestException

Throws:

InvalidRequestException

setKeyspace

public void setKeyspace(java.lang.String ks)
                 throws InvalidRequestException

Throws:

InvalidRequestException

setNoCompactMode

public void setNoCompactMode()

isNoCompactMode

public boolean isNoCompactMode()

login

public void login(AuthenticatedUser user)
           throws AuthenticationException

Attempts to login the given user.

Throws:

AuthenticationException

hasAllKeyspacesAccess

public void hasAllKeyspacesAccess(Permission perm)
                           throws UnauthorizedException

Throws:

UnauthorizedException

hasKeyspaceAccess

public void hasKeyspaceAccess(java.lang.String keyspace,
                              Permission perm)
                       throws UnauthorizedException,
                              InvalidRequestException

Throws:

UnauthorizedException

InvalidRequestException

hasColumnFamilyAccess

public void hasColumnFamilyAccess(java.lang.String keyspace,
                                  java.lang.String columnFamily,
                                  Permission perm)
                           throws UnauthorizedException,
                                  InvalidRequestException

Throws:

UnauthorizedException

InvalidRequestException

hasColumnFamilyAccess

public void hasColumnFamilyAccess(CFMetaData cfm,
                                  Permission perm)
                           throws UnauthorizedException,
                                  InvalidRequestException

Throws:

UnauthorizedException

InvalidRequestException

ensureHasPermission

public void ensureHasPermission(Permission perm,
                                IResource resource)
                         throws UnauthorizedException

Throws:

UnauthorizedException

ensureHasPermission

public void ensureHasPermission(Permission permission,
                                Function function)

validateLogin

public void validateLogin()
                   throws UnauthorizedException

Throws:

UnauthorizedException

ensureNotAnonymous

public void ensureNotAnonymous()
                        throws UnauthorizedException

Throws:

UnauthorizedException

ensureIsSuper

public void ensureIsSuper(java.lang.String message)
                   throws UnauthorizedException

Throws:

UnauthorizedException

getUser

public AuthenticatedUser getUser()

getCQLSupportedVersion

public static CassandraVersion[] getCQLSupportedVersion()