Package me.ahoo.cosid.spring.redis

Class SpringRedisMachineLeaseStore

java.lang.Object
me.ahoo.cosid.spring.redis.SpringRedisMachineLeaseStore
All Implemented Interfaces:
MachineLeaseStore
public class SpringRedisMachineLeaseStore extends Object implements MachineLeaseStore
MachineLeaseStore on Redis: one atomic Lua script per primitive (machine_lease.lua).

It uses the same keys as the 3.4 machine id distributor (cosid:{namespace}:itc_idx, revert, adder, stable), so instances running either one, and 3.4 instances, can share a namespace during an upgrade. The watermark, renewal time and version of each machine id are kept in cosid:{namespace}:lease; the 3.4 keys hold a timestamp that is at least all of them, which 3.4 reads as its last timestamp. A machine id last written by a 3.4 instance is read with that timestamp as its watermark, renewal time and version. The server clock is Redis' TIME. Every command is bounded by the RedisCommandTimeout.

Since:
3.4.0

  • Field Details

    • MACHINE_LEASE

      public static final org.springframework.data.redis.core.script.RedisScript<List> MACHINE_LEASE

  • Constructor Details

    • SpringRedisMachineLeaseStore

      public SpringRedisMachineLeaseStore(org.springframework.data.redis.core.StringRedisTemplate redisTemplate, RedisCommandTimeout commandTimeout)
      Create a Redis lease store.
      Parameters:
      commandTimeout - bounds every command, which may run under the lease distributor's lock: must be enabled

  • Method Details

    • withCommandTimeout

      public SpringRedisMachineLeaseStore withCommandTimeout(RedisCommandTimeout commandTimeout)
      The same store with another command timeout, for example a longer one for the distribution at startup, where the first command also pays for connecting.

    • getCommandTimeout

      public RedisCommandTimeout getCommandTimeout()

    • claimSelf

      public Optional<Lease> claimSelf(String namespace, InstanceId instanceId, long now)
      Description copied from interface: MachineLeaseStore
      Take back the lease this instance already holds, renewing it to now, whether or not it has expired. The watermark is raised to at least now and the stored renewed at.
      Specified by:
      claimSelf in interface MachineLeaseStore
      Returns:
      the renewed lease, or empty if the instance holds none (it was released or recycled)

    • claimReleased

      public Optional<Lease> claimReleased(String namespace, InstanceId instanceId, int maxMachineId, long now)
      Description copied from interface: MachineLeaseStore
      Take a machine id that a non-stable instance released on shutdown.
      Specified by:
      claimReleased in interface MachineLeaseStore
      maxMachineId - the largest machine id allowed: released ids above it (left over from a larger machine bit) are never returned
      Returns:
      the new lease, or empty if no released machine id up to maxMachineId is left

    • claimNew

      public Optional<Lease> claimNew(String namespace, InstanceId instanceId, int maxMachineId, long now)
      Description copied from interface: MachineLeaseStore
      Take the next machine id that was never used in the namespace.
      Specified by:
      claimNew in interface MachineLeaseStore
      maxMachineId - the largest machine id allowed
      Returns:
      the new lease, or empty if every machine id up to maxMachineId is in use

    • claimExpired

      public Optional<Lease> claimExpired(String namespace, InstanceId instanceId, int maxMachineId, long expiredBefore, long now)
      Description copied from interface: MachineLeaseStore
      Take over a machine id whose owner has not renewed it since expiredBefore. Leases of stable instances are never taken over.
      Specified by:
      claimExpired in interface MachineLeaseStore
      maxMachineId - the largest machine id allowed: expired ids above it are never returned
      expiredBefore - leases renewed at or before this time are expired
      Returns:
      the new lease, or empty if no lease up to maxMachineId has expired

    • renew

      public Optional<Lease> renew(Lease lease, long now)
      Description copied from interface: MachineLeaseStore
      Renew a lease to now if it is still the current version, even when now is before the stored renewed at (the store clock moved back). The watermark is unchanged.
      Specified by:
      renew in interface MachineLeaseStore
      Returns:
      the renewed lease, or empty if the lease was taken over, released or changed since

    • release

      public boolean release(Lease lease, long watermark)
      Description copied from interface: MachineLeaseStore
      Release a lease on shutdown, if it is still the current version. A stable instance keeps its machine id (only the watermark is updated); otherwise the machine id becomes available to MachineLeaseStore.claimReleased(java.lang.String, me.ahoo.cosid.machine.InstanceId, int, long).
      Specified by:
      release in interface MachineLeaseStore
      watermark - the generator's last timestamp: the watermark becomes at least this, so that the next owner waits if its clock is behind
      Returns:
      false if the lease was taken over or changed since

    • serverTime

      public long serverTime()
      Redis' TIME, in milliseconds.
      Specified by:
      serverTime in interface MachineLeaseStore