Package org.apache.accumulo.core.clientImpl

Class InstanceOperationsImpl

    • Constructor Detail

      • InstanceOperationsImpl

        public InstanceOperationsImpl​(ClientContext context)

    • Method Detail

      • modifyProperties

        public Map<String,​String> modifyProperties​(Consumer<Map<String,​String>> mapMutator)
                                          throws AccumuloException,
                                                 AccumuloSecurityException,
                                                 IllegalArgumentException
        Description copied from interface: InstanceOperations
        Modify system properties using a Consumer that accepts a mutable map containing the current system property overrides stored in ZooKeeper. If the supplied Consumer alters the map without throwing an Exception, then the resulting map will atomically replace the current system property overrides in ZooKeeper. Only properties which can be stored in ZooKeeper will be accepted.

        Accumulo has multiple layers of properties that for many APIs and SPIs are presented as a single merged view. This API does not offer that merged view, it only offers the properties set at the system layer to the mapMutator.

        This new API offers two distinct advantages over the older InstanceOperations.setProperty(String, String) API. The older API offered the ability to unconditionally set a single property. This new API offers the following.

        • Ability to unconditionally set multiple properties atomically. If five properties are mutated by this API, then eventually all of the servers will see those changes all at once. This is really important for configuring something like a scan iterator that requires setting multiple properties.
        • Ability to conditionally set multiple properties atomically. With this new API a snapshot of the current instance configuration is passed in to the mapMutator. Code can inspect the current config and decide what if any changes it would like to make. If the config changes while mapMutator is doing inspection and modification, then those actions will be ignored and it will be called again with the latest snapshot of the config.

        Below is an example of using this API to conditionally set some instance properties. If while trying to set the compaction planner properties another process modifies the manager balancer properties, then it would automatically retry and call the lambda again with the latest snapshot of instance properties. 

                 
             AccumuloClient client = getClient();
             Map<String,String> acceptedProps = client.instanceOperations().modifyProperties(currProps -> {
               var planner = currProps.get("tserver.compaction.major.service.default.planner");
               //This code will only change the compaction planner if its currently set to default settings.
               //The endsWith() function was used to make the example short, would be better to use equals().
               if(planner != null && planner.endsWith("DefaultCompactionPlanner") {
                 // tservers will eventually see these compaction planner changes and when they do they will see all of the changes at once
                 currProps.keySet().removeIf(
                    prop -> prop.startsWith("tserver.compaction.major.service.default.planner.opts."));
                 currProps.put("tserver.compaction.major.service.default.planner","MyPlannerClassName");
                 currProps.put("tserver.compaction.major.service.default.planner.opts.myOpt1","val1");
                 currProps.put("tserver.compaction.major.service.default.planner.opts.myOpt2","val2");
                }
             });

             // Since three properties were set may want to check for the values of all
             // three, just checking one in this example to keep it short.
             if("MyPlannerClassName".equals(acceptedProps.get("tserver.compaction.major.service.default.planner"))){
                // the compaction planner change was accepted or already existed, so take action for that outcome
             } else {
                // the compaction planner change was not done, so take action for that outcome
             }
           
         }
        Specified by:
        modifyProperties in interface InstanceOperations
        Parameters:
        mapMutator - This consumer should modify the passed snapshot of instance properties to contain the desired keys and values. It should be safe for Accumulo to call this consumer multiple times, this may be done automatically when certain retryable errors happen. The consumer should probably avoid accessing the Accumulo client as that could lead to undefined behavior.
        Returns:
        The map that became Accumulo's new properties for this table. This map is immutable and contains the snapshot passed to mapMutator and the changes made by mapMutator.
        Throws:
        AccumuloException - if a general error occurs
        AccumuloSecurityException - if the user does not have permission
        IllegalArgumentException - if the Consumer alters the map by adding properties that cannot be stored in ZooKeeper

      • getTabletServers

        public List<String> getTabletServers()
        Description copied from interface: InstanceOperations
        List the currently active tablet servers participating in the accumulo instance
        Specified by:
        getTabletServers in interface InstanceOperations
        Returns:
        A list of currently active tablet servers.

      • lookupInstanceName

        public static String lookupInstanceName​(ZooCache zooCache,
                                        InstanceId instanceId)
        Given a zooCache and instanceId, look up the instance name.