common/thrift/StatestoreService.thrift - impala - Git at Google

 // Licensed to the Apache Software Foundation (ASF) under one
 // or more contributor license agreements.  See the NOTICE file
 // distributed with this work for additional information
 // regarding copyright ownership.  The ASF licenses this file
 // to you under the Apache License, Version 2.0 (the
 // "License"); you may not use this file except in compliance
 // with the License.  You may obtain a copy of the License at
 //
 //   http://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing,
 // software distributed under the License is distributed on an
 // "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 // KIND, either express or implied.  See the License for the
 // specific language governing permissions and limitations
 // under the License.

 namespace cpp impala
 namespace java org.apache.impala.thrift

 include "Status.thrift"
 include "Types.thrift"
 include "CatalogService.thrift"

 enum StatestoreServiceVersion {
    V1 = 0
    // There is back version incompatibility. We need to increase the service version
    // for Statestore so that Statestore will refuse the registration requests from
    // the incompatible subscribers.
    V2 = 1
 }

 // Description of a single entry in a list of heavy memory usage queries
 struct THeavyMemoryQuery {

   // The memory consumption of the query
   1: required i64 memory_consumed;

   // The Id of the query
   2: required Types.TUniqueId queryId;
 }


 // Structure serialized for the topic AdmissionController::IMPALA_REQUEST_QUEUE_TOPIC.
 // Statistics for a single admission control pool. The topic key is of the form
 // "<pool_name>!<backend_id>".
 struct TPoolStats {
   // The current number of requests admitted by this host's admission controller
   // and are currently running. This is an instantaneous value (as opposed to a
   // cumulative sum).
   1: required i64 num_admitted_running;

   // The current number of queued requests. This is an instantaneous value.
   2: required i64 num_queued;

   // The memory (in bytes) currently reserved on this backend for use by queries in this
   // pool. E.g.  when a query which reserves 10G/host admitted to this pool begins
   // execution on this impalad, this value increases by 10G. Any other impalads executing
   // this query will also increment their backend_mem_reserved by 10G.
   3: required i64 backend_mem_reserved;

   // More entries about queries running in the backend.
   //
   // List of queries with top-k memory consumptions.
   4: required list<THeavyMemoryQuery> heavy_memory_queries;

   // Min memory consumption among all queries.
   5: required i64 min_memory_consumed;

   // Max memory consumption among all queries.
   6: required i64 max_memory_consumed;

   // Total memory consumption among all queries.
   7: required i64 total_memory_consumed;

   // The number of queries that have live fragments taking up memory on the host in
   // a pool. These queries must be tracked by some query mem trackers. In comparison,
   // num_admitted_running tracks the number of queries admitted in a host.
   8: required i64 num_running;
 }

 struct THostStats {
   // The mem reserved for a query that is currently executing is its memory limit, if
   // set (which should be the common case with admission control). Otherwise, if the
   // query has no limit or the query is finished executing, the current consumption
   // (tracked by its query mem tracker) is used.
   1: required i64 mem_reserved;

   // The per host mem admitted only for the queries admitted locally.
   2: required i64 mem_admitted;

   // The per host number of queries admitted only for the queries admitted locally.
   3: required i64 num_admitted;

   // The per host number of slots in use for the queries admitted locally.
   4: required i64 slots_in_use;
 }

 struct TPerHostStatsUpdateElement {
     1: required string host_addr;
     2: required THostStats stats;
 }

 struct TPerHostStatsUpdate {
   // This stores per-host statistics which are used during admission and by HTTP
   // handlers to query admission control statistics for currently registered backends.
   1: required list<TPerHostStatsUpdateElement> per_host_stats;
 }

 // Description of a single entry in a topic
 struct TTopicItem {
   // Human-readable topic entry identifier
   1: required string key;

   // Byte-string value for this topic entry. May not be null-terminated (in that it may
   // contain null bytes). It can be non-empty when deleted is true. This is needed when
   // subscribers require additional information not captured in the item key to process
   // the deleted item (e.g., catalog version of deleted catalog object).
   2: required string value;

   // If true, this item was deleted. When false, this TTopicItem need not be included in
   // non-delta TTopicDelta's since the latest version of every still-present topic item
   // will be included.
   3: required bool deleted = false;
 }

 // Set of changes to a single topic, sent from the statestore to a subscriber as well as
 // from a subscriber to the statestore.
 struct TTopicDelta {
   // Name of the topic this delta applies to
   1: required string topic_name;

   // When is_delta=true, a list of changes to topic entries, including deletions, within
   // [from_version, to_version].
   // When is_delta=false, this is the list of all non-delete topic entries for
   // [0, to_version], which can be used to reconstruct the topic from scratch.
   2: required list<TTopicItem> topic_entries;

   // True if entries / deletions are relative to the topic at versions [0, from_version].
   3: required bool is_delta;

   // The Topic version range this delta covers. If there have been changes to the topic,
   // the update will include all changes in the range: [from_version, to_version).
   // If there have been no changes in the topic the from_version will match the
   // to_version. The from_version will always be 0 for non-delta updates.
   // If this is an update being sent from a subscriber to the statestore, the from_version
   // is set only when recovering from an inconsistent state, to the last version of the
   // topic the subscriber successfully processed. The value of to_version doesn't depend
   // on whether the update is delta or not.
   4: optional i64 from_version
   5: optional i64 to_version

   // The minimum topic version of all subscribers to the topic. This can be used to
   // determine when all subscribers have successfully processed a specific update.
   // This is guaranteed because no subscriber will ever be sent a topic containing
   // keys with a version < min_subscriber_topic_version. Only used when sending an update
   // from the statestore to a subscriber.
   6: optional i64 min_subscriber_topic_version

   // If set and true the statestore must clear the existing topic entries (if any) before
   // applying the entries in topic_entries.
   7: optional bool clear_topic_entries
 }

 // Description of a topic to subscribe to as part of a RegisterSubscriber call
 struct TTopicRegistration {
   // Human readable key for this topic
   1: required string topic_name;

   // True if updates to this topic from this subscriber should be removed upon the
   // subscriber's failure or disconnection
   2: required bool is_transient;

   // If true, min_subscriber_topic_version is computed and set in topic updates sent
   // to this subscriber to this subscriber. Should only be set to true if this is
   // actually required - computing the version is relatively expensive compared to
   // other aspects of preparing topic updates - see IMPALA-6816.
   3: required bool populate_min_subscriber_topic_version = false;

   // Restrict the items to receive on this subscription to only those items
   // starting with the given prefix.
   //
   // If this is not specified, all items will be subscribed to.
   4: optional string filter_prefix
 }

 // Define the type for statestore subscriber
 enum TStatestoreSubscriberType {
   UNKNOWN = 0
   ADMISSIOND = 1
   CATALOGD = 2
   COORDINATOR = 3
   EXECUTOR = 4
   COORDINATOR_EXECUTOR = 5
 }

 // To support statestore HA, the standby statestore instance monitor the state of active
 // statestore instance by collecting connection states between active statestore instance
 // and subscribers. This enum define the connection states reported by subscribers in
 // heartbeat response message.
 enum TStatestoreConnState {
    OK = 0
    FAILED = 1
    UNKNOWN = 2
 }

 // Additional registration info for catalog daemon.
 struct TCatalogRegistration {
   // Protocol version of Catalog service.
   1: required CatalogService.CatalogServiceVersion protocol;

   // Address of catalogd.
   2: required Types.TNetworkAddress address;

   // True if CatalogD HA is enabled.
   3: optional bool enable_catalogd_ha;

   // True if the catalogd instance is started as active instance.
   4: optional bool force_catalogd_active;
 }

 struct TRegisterSubscriberRequest {
   // Protocol version of the subscriber
   1: required StatestoreServiceVersion protocol_version =
       StatestoreServiceVersion.V2

   // Unique, human-readable identifier for this subscriber
   2: required string subscriber_id;

   // Location of the StatestoreSubscriberService that this subscriber runs
   3: required Types.TNetworkAddress subscriber_location;

   // List of topics to subscribe to
   4: required list<TTopicRegistration> topic_registrations;

   // Subscribe type
   5: optional TStatestoreSubscriberType subscriber_type;

   // Indicate if the subscriber wishes to be notified of changes to the catalogd.
   // When it's set as true, statestore will send UpdateCatalogd RPC to the subscriber
   // once there is catalogd change. Currently it as true for coordinators. In future,
   // it will be set as true for catalogd when supporting Catalog HA.
   6: optional bool subscribe_catalogd_change;

   // Set iff this subscriber is catalogd.
   7: optional TCatalogRegistration catalogd_registration;
 }

 struct TRegisterSubscriberResponse {
   // Whether the call was executed correctly at the application level
   1: required Status.TStatus status;

   // Unique identifier for this registration. Changes with every call to
   // RegisterSubscriber().
   2: optional Types.TUniqueId registration_id;

   // Protocol version of the statestore
   3: optional StatestoreServiceVersion protocol_version;

   // Unique identifier for the statestore instance. It could be changed for a new
   // call RegisterSubscriber() if the statestore instance has been restarted since
   // last registration.
   4: optional Types.TUniqueId statestore_id;

   // Catalog registration info.
   5: optional TCatalogRegistration catalogd_registration;

   // The version of active catalogd
   6: optional i64 catalogd_version;

   // Active state of this Statestore instance.
   7: optional bool statestore_is_active;

   // The version of active statestored
   8: optional i64 active_statestored_version;
 }

 struct TGetProtocolVersionRequest {
   // Protocol version of the subscriber
   1: required StatestoreServiceVersion protocol_version =
       StatestoreServiceVersion.V2
 }

 struct TGetProtocolVersionResponse {
   // whether the call was executed correctly at the application level
   1: required Status.TStatus status;

   // Protocol version of the statestore
   2: required StatestoreServiceVersion protocol_version;

   // Unique identifier for the statestore instance.
   3: optional Types.TUniqueId statestore_id;
 }

 struct TSetStatestoreDebugActionRequest {
   // Protocol version of the subscriber
   1: required StatestoreServiceVersion protocol_version =
       StatestoreServiceVersion.V2

   // Disable network for statestored if it's set as true so that statestored does not
   // sent heartbeat and HA handshake messages. Enable network if it's set as false.
   // This is used to simulate network failure for unit-test.
   2: optional bool disable_network;
 }

 struct TSetStatestoreDebugActionResponse {
   // whether the call was executed correctly at the application level
   1: required Status.TStatus status;
 }

 service StatestoreService {
   // Register a single subscriber. Note that after a subscriber is registered, no new
   // topics may be added.
   TRegisterSubscriberResponse RegisterSubscriber(1: TRegisterSubscriberRequest params);

   // Get protocol version of the statestore
   TGetProtocolVersionResponse GetProtocolVersion(1: TGetProtocolVersionRequest params);

   // Set debug action for the statestored.
   // This API is only used for unit-test.
   TSetStatestoreDebugActionResponse SetStatestoreDebugAction(
       1: TSetStatestoreDebugActionRequest params);
 }

 struct TUpdateStateRequest {
   // Protocol version of the statestore
   1: required StatestoreServiceVersion protocol_version =
       StatestoreServiceVersion.V2

   // Map from topic name to a list of changes for that topic.
   2: required map<string, TTopicDelta> topic_deltas;

   // Registration ID for the last known registration from this subscriber.
   3: optional Types.TUniqueId registration_id;

   // Unique identifier for the statestore instance.
   4: optional Types.TUniqueId statestore_id;
 }

 struct TUpdateStateResponse {
   // Whether the call was executed correctly at the application level
   1: required Status.TStatus status;

   // List of updates published by the subscriber to be made centrally by the statestore
   2: required list<TTopicDelta> topic_updates;

   // True if this update was skipped by the subscriber. This is distinguished from a
   // non-OK status since the former indicates an error which contributes to the
   // statestore's view of a subscriber's liveness.
   3: optional bool skipped;
 }

 struct THeartbeatRequest {
   // Protocol version of the statestore
   1: optional StatestoreServiceVersion protocol_version =
       StatestoreServiceVersion.V2

   // registration_id of the receiver
   2: optional Types.TUniqueId registration_id;

   // Unique identifier for the statestore instance.
   3: optional Types.TUniqueId statestore_id;

   // Flag set by standby Statestore instance to request the connection state between
   // active statestore and the subscriber.
   4: optional bool request_statestore_conn_state;
 }

 struct THeartbeatResponse {
   // Whether the call was executed correctly at the application level
   1: required Status.TStatus status;

   // Connection state between active statestore and the subscriber reported by
   // the subscriber.
   2: optional TStatestoreConnState statestore_conn_state;
 }

 struct TUpdateCatalogdRequest {
   // Protocol version of the statestore
   1: required StatestoreServiceVersion protocol_version =
       StatestoreServiceVersion.V2

   // registration_id of the receiver
   2: required Types.TUniqueId registration_id;

   // Unique identifier for the statestore instance.
   3: required Types.TUniqueId statestore_id;

   // The version of active catalogd
   4: required i64 catalogd_version;

   // Catalog registration info.
   5: required TCatalogRegistration catalogd_registration;
 }

 struct TUpdateCatalogdResponse {
   // Whether the call was executed correctly at the application level
   1: required Status.TStatus status;

   // True if this update was skipped by the subscriber. This is distinguished from a
   // non-OK status since the former indicates an error which contributes to the
   // statestore's view of a subscriber's liveness.
   2: optional bool skipped;
 }

 struct TUpdateStatestoredRoleRequest {
   // Protocol version of the statestore
   1: required StatestoreServiceVersion protocol_version =
       StatestoreServiceVersion.V2;

   // registration_id of the receiver
   2: required Types.TUniqueId registration_id;

   // Unique identifier for the statestore instance.
   3: required Types.TUniqueId statestore_id;

   // Monotonously increasing number
   4: required i64 active_statestored_version;

   // Active state of Statestore instance
   5: required bool is_active;

   // Send elected active catalogd along with the role of active statestore.
   // The version of active catalogd. Don't set this catalogd_version and
   // catalogd_registration if active catalogd has not been elected.
   6: optional i64 catalogd_version;

   // Catalog registration info.
   7: optional TCatalogRegistration catalogd_registration;
 }

 struct TUpdateStatestoredRoleResponse {
   // Whether the call was executed correctly
   1: required Status.TStatus status;

   // True if this update was skipped by the subscriber.
   2: optional bool skipped;
 }

 service StatestoreSubscriber {
   // Called when the statestore sends a topic update. The request contains a map of
   // topic names to TTopicDelta updates, sent from the statestore to the subscriber. Each
   // of these delta updates will contain a list of additions to the topic and a list of
   // deletions from the topic.
   // In response, the subscriber returns an aggregated list of updates to topic(s) to
   // the statestore. Each update is a TTopicDelta that contains a list of additions to
   // the topic and a list of deletions from the topic. Additionally, if a subscriber has
   // received an unexpected delta update version range, they can request a new delta
   // update based off a specific version from the statestore. The next statestore
   // delta update will be based off of the version the subscriber requested.
   //
   // When Statestore HA is enabled, two statestore instances will be created in an Impala
   // cluster as Active-Passive HA pair. All subscribers should register to both
   // statestore instances so that two statestore instances have same set of subscribers.
   // Both Statestore instances send heartbeat to their subscribers, but only active
   // statestore instance sends topic update to its subscribers.
   TUpdateStateResponse UpdateState(1: TUpdateStateRequest params);

   // Called when the statestore sends a heartbeat.
   THeartbeatResponse Heartbeat(1: THeartbeatRequest params);

   // Called when active catalogd has been updated.
   TUpdateCatalogdResponse UpdateCatalogd(1: TUpdateCatalogdRequest params);

   // Called by standby statestore when the Statestore service failover happens, which
   // causes the active states of statestoreds are changed.
   TUpdateStatestoredRoleResponse UpdateStatestoredRole(
       1: TUpdateStatestoredRoleRequest params);
 }

 struct TStatestoreHaHandshakeRequest {
   // Service's version of source Statestore instance
   1: required StatestoreServiceVersion src_protocol_version =
       StatestoreServiceVersion.V2;

   // Instance id of source Statestore instance
   2: required Types.TUniqueId src_statestore_id;

   // Address of the Statestore that source statestore instance runs
   3: required string src_statestore_address;

   // True if starting flag statestore_force_active is set as true for source statestore
   // instance.
   4: required bool src_force_active;
 }

 struct TStatestoreHaHandshakeResponse {
   // Whether the call was executed correctly
   1: required Status.TStatus status;

   // Service's version of destination Statestore instance
   2: required StatestoreServiceVersion dst_protocol_version =
       StatestoreServiceVersion.V2;

   // Instance id of destination Statestore instance
   3: required Types.TUniqueId dst_statestore_id;

   // Indication if the destination Statestore is active for preemption. Source
   // statestore should set itself as inactive if dst_statestore_active is set as true.
   // Otherwise, source statestore sets itself as active.
   4: required bool dst_statestore_active;
 }

 struct TStatestoreHaHeartbeatRequest {
   // Service's version of source Statestore instance
   1: required StatestoreServiceVersion protocol_version =
       StatestoreServiceVersion.V2;

   // Destination Statestore instance id
   2: required Types.TUniqueId dst_statestore_id;

   // Source Statestore instance id
   3: required Types.TUniqueId src_statestore_id;
 }

 struct TStatestoreHaHeartbeatResponse {
   1: required Status.TStatus status;
 }

 // Service for communication between two statestore instances in an Active-Passive
 // HA (High Availability) pair.
 service StatestoreHaService {
   // StatestoreHaHandshake: negotiate active role between two instances during startup.
   TStatestoreHaHandshakeResponse StatestoreHaHandshake(
       1: TStatestoreHaHandshakeRequest params);

   // StatestoreHaHeartbeat: active statestore sends heartbeat to standby statestore.
   TStatestoreHaHeartbeatResponse StatestoreHaHeartbeat(
       1: TStatestoreHaHeartbeatRequest params);
 }
	// Licensed to the Apache Software Foundation (ASF) under one
	// or more contributor license agreements. See the NOTICE file
	// distributed with this work for additional information
	// regarding copyright ownership. The ASF licenses this file
	// to you under the Apache License, Version 2.0 (the
	// "License"); you may not use this file except in compliance
	// with the License. You may obtain a copy of the License at
	//
	// http://www.apache.org/licenses/LICENSE-2.0
	//
	// Unless required by applicable law or agreed to in writing,
	// software distributed under the License is distributed on an
	// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
	// KIND, either express or implied. See the License for the
	// specific language governing permissions and limitations
	// under the License.

	namespace cpp impala
	namespace java org.apache.impala.thrift

	include "Status.thrift"
	include "Types.thrift"
	include "CatalogService.thrift"

	enum StatestoreServiceVersion {
	V1 = 0
	// There is back version incompatibility. We need to increase the service version
	// for Statestore so that Statestore will refuse the registration requests from
	// the incompatible subscribers.
	V2 = 1
	}

	// Description of a single entry in a list of heavy memory usage queries
	struct THeavyMemoryQuery {

	// The memory consumption of the query
	1: required i64 memory_consumed;

	// The Id of the query
	2: required Types.TUniqueId queryId;
	}


	// Structure serialized for the topic AdmissionController::IMPALA_REQUEST_QUEUE_TOPIC.
	// Statistics for a single admission control pool. The topic key is of the form
	// "<pool_name>!<backend_id>".
	struct TPoolStats {
	// The current number of requests admitted by this host's admission controller
	// and are currently running. This is an instantaneous value (as opposed to a
	// cumulative sum).
	1: required i64 num_admitted_running;

	// The current number of queued requests. This is an instantaneous value.
	2: required i64 num_queued;

	// The memory (in bytes) currently reserved on this backend for use by queries in this
	// pool. E.g. when a query which reserves 10G/host admitted to this pool begins
	// execution on this impalad, this value increases by 10G. Any other impalads executing
	// this query will also increment their backend_mem_reserved by 10G.
	3: required i64 backend_mem_reserved;

	// More entries about queries running in the backend.
	//
	// List of queries with top-k memory consumptions.
	4: required list<THeavyMemoryQuery> heavy_memory_queries;

	// Min memory consumption among all queries.
	5: required i64 min_memory_consumed;

	// Max memory consumption among all queries.
	6: required i64 max_memory_consumed;

	// Total memory consumption among all queries.
	7: required i64 total_memory_consumed;

	// The number of queries that have live fragments taking up memory on the host in
	// a pool. These queries must be tracked by some query mem trackers. In comparison,
	// num_admitted_running tracks the number of queries admitted in a host.
	8: required i64 num_running;
	}

	struct THostStats {
	// The mem reserved for a query that is currently executing is its memory limit, if
	// set (which should be the common case with admission control). Otherwise, if the
	// query has no limit or the query is finished executing, the current consumption
	// (tracked by its query mem tracker) is used.
	1: required i64 mem_reserved;

	// The per host mem admitted only for the queries admitted locally.
	2: required i64 mem_admitted;

	// The per host number of queries admitted only for the queries admitted locally.
	3: required i64 num_admitted;

	// The per host number of slots in use for the queries admitted locally.
	4: required i64 slots_in_use;
	}

	struct TPerHostStatsUpdateElement {
	1: required string host_addr;
	2: required THostStats stats;
	}

	struct TPerHostStatsUpdate {
	// This stores per-host statistics which are used during admission and by HTTP
	// handlers to query admission control statistics for currently registered backends.
	1: required list<TPerHostStatsUpdateElement> per_host_stats;
	}

	// Description of a single entry in a topic
	struct TTopicItem {
	// Human-readable topic entry identifier
	1: required string key;

	// Byte-string value for this topic entry. May not be null-terminated (in that it may
	// contain null bytes). It can be non-empty when deleted is true. This is needed when
	// subscribers require additional information not captured in the item key to process
	// the deleted item (e.g., catalog version of deleted catalog object).
	2: required string value;

	// If true, this item was deleted. When false, this TTopicItem need not be included in
	// non-delta TTopicDelta's since the latest version of every still-present topic item
	// will be included.
	3: required bool deleted = false;
	}

	// Set of changes to a single topic, sent from the statestore to a subscriber as well as
	// from a subscriber to the statestore.
	struct TTopicDelta {
	// Name of the topic this delta applies to
	1: required string topic_name;

	// When is_delta=true, a list of changes to topic entries, including deletions, within
	// [from_version, to_version].
	// When is_delta=false, this is the list of all non-delete topic entries for
	// [0, to_version], which can be used to reconstruct the topic from scratch.
	2: required list<TTopicItem> topic_entries;

	// True if entries / deletions are relative to the topic at versions [0, from_version].
	3: required bool is_delta;

	// The Topic version range this delta covers. If there have been changes to the topic,
	// the update will include all changes in the range: [from_version, to_version).
	// If there have been no changes in the topic the from_version will match the
	// to_version. The from_version will always be 0 for non-delta updates.
	// If this is an update being sent from a subscriber to the statestore, the from_version
	// is set only when recovering from an inconsistent state, to the last version of the
	// topic the subscriber successfully processed. The value of to_version doesn't depend
	// on whether the update is delta or not.
	4: optional i64 from_version
	5: optional i64 to_version

	// The minimum topic version of all subscribers to the topic. This can be used to
	// determine when all subscribers have successfully processed a specific update.
	// This is guaranteed because no subscriber will ever be sent a topic containing
	// keys with a version < min_subscriber_topic_version. Only used when sending an update
	// from the statestore to a subscriber.
	6: optional i64 min_subscriber_topic_version

	// If set and true the statestore must clear the existing topic entries (if any) before
	// applying the entries in topic_entries.
	7: optional bool clear_topic_entries
	}

	// Description of a topic to subscribe to as part of a RegisterSubscriber call
	struct TTopicRegistration {
	// Human readable key for this topic
	1: required string topic_name;

	// True if updates to this topic from this subscriber should be removed upon the
	// subscriber's failure or disconnection
	2: required bool is_transient;

	// If true, min_subscriber_topic_version is computed and set in topic updates sent
	// to this subscriber to this subscriber. Should only be set to true if this is
	// actually required - computing the version is relatively expensive compared to
	// other aspects of preparing topic updates - see IMPALA-6816.
	3: required bool populate_min_subscriber_topic_version = false;

	// Restrict the items to receive on this subscription to only those items
	// starting with the given prefix.
	//
	// If this is not specified, all items will be subscribed to.
	4: optional string filter_prefix
	}

	// Define the type for statestore subscriber
	enum TStatestoreSubscriberType {
	UNKNOWN = 0
	ADMISSIOND = 1
	CATALOGD = 2
	COORDINATOR = 3
	EXECUTOR = 4
	COORDINATOR_EXECUTOR = 5
	}

	// To support statestore HA, the standby statestore instance monitor the state of active
	// statestore instance by collecting connection states between active statestore instance
	// and subscribers. This enum define the connection states reported by subscribers in
	// heartbeat response message.
	enum TStatestoreConnState {
	OK = 0
	FAILED = 1
	UNKNOWN = 2
	}

	// Additional registration info for catalog daemon.
	struct TCatalogRegistration {
	// Protocol version of Catalog service.
	1: required CatalogService.CatalogServiceVersion protocol;

	// Address of catalogd.
	2: required Types.TNetworkAddress address;

	// True if CatalogD HA is enabled.
	3: optional bool enable_catalogd_ha;

	// True if the catalogd instance is started as active instance.
	4: optional bool force_catalogd_active;
	}

	struct TRegisterSubscriberRequest {
	// Protocol version of the subscriber
	1: required StatestoreServiceVersion protocol_version =
	StatestoreServiceVersion.V2

	// Unique, human-readable identifier for this subscriber
	2: required string subscriber_id;

	// Location of the StatestoreSubscriberService that this subscriber runs
	3: required Types.TNetworkAddress subscriber_location;

	// List of topics to subscribe to
	4: required list<TTopicRegistration> topic_registrations;

	// Subscribe type
	5: optional TStatestoreSubscriberType subscriber_type;

	// Indicate if the subscriber wishes to be notified of changes to the catalogd.
	// When it's set as true, statestore will send UpdateCatalogd RPC to the subscriber
	// once there is catalogd change. Currently it as true for coordinators. In future,
	// it will be set as true for catalogd when supporting Catalog HA.
	6: optional bool subscribe_catalogd_change;

	// Set iff this subscriber is catalogd.
	7: optional TCatalogRegistration catalogd_registration;
	}

	struct TRegisterSubscriberResponse {
	// Whether the call was executed correctly at the application level
	1: required Status.TStatus status;

	// Unique identifier for this registration. Changes with every call to
	// RegisterSubscriber().
	2: optional Types.TUniqueId registration_id;

	// Protocol version of the statestore
	3: optional StatestoreServiceVersion protocol_version;

	// Unique identifier for the statestore instance. It could be changed for a new
	// call RegisterSubscriber() if the statestore instance has been restarted since
	// last registration.
	4: optional Types.TUniqueId statestore_id;

	// Catalog registration info.
	5: optional TCatalogRegistration catalogd_registration;

	// The version of active catalogd
	6: optional i64 catalogd_version;

	// Active state of this Statestore instance.
	7: optional bool statestore_is_active;

	// The version of active statestored
	8: optional i64 active_statestored_version;
	}

	struct TGetProtocolVersionRequest {
	// Protocol version of the subscriber
	1: required StatestoreServiceVersion protocol_version =
	StatestoreServiceVersion.V2
	}

	struct TGetProtocolVersionResponse {
	// whether the call was executed correctly at the application level
	1: required Status.TStatus status;

	// Protocol version of the statestore
	2: required StatestoreServiceVersion protocol_version;

	// Unique identifier for the statestore instance.
	3: optional Types.TUniqueId statestore_id;
	}

	struct TSetStatestoreDebugActionRequest {
	// Protocol version of the subscriber
	1: required StatestoreServiceVersion protocol_version =
	StatestoreServiceVersion.V2

	// Disable network for statestored if it's set as true so that statestored does not
	// sent heartbeat and HA handshake messages. Enable network if it's set as false.
	// This is used to simulate network failure for unit-test.
	2: optional bool disable_network;
	}

	struct TSetStatestoreDebugActionResponse {
	// whether the call was executed correctly at the application level
	1: required Status.TStatus status;
	}

	service StatestoreService {
	// Register a single subscriber. Note that after a subscriber is registered, no new
	// topics may be added.
	TRegisterSubscriberResponse RegisterSubscriber(1: TRegisterSubscriberRequest params);

	// Get protocol version of the statestore
	TGetProtocolVersionResponse GetProtocolVersion(1: TGetProtocolVersionRequest params);

	// Set debug action for the statestored.
	// This API is only used for unit-test.
	TSetStatestoreDebugActionResponse SetStatestoreDebugAction(
	1: TSetStatestoreDebugActionRequest params);
	}

	struct TUpdateStateRequest {
	// Protocol version of the statestore
	1: required StatestoreServiceVersion protocol_version =
	StatestoreServiceVersion.V2

	// Map from topic name to a list of changes for that topic.
	2: required map<string, TTopicDelta> topic_deltas;

	// Registration ID for the last known registration from this subscriber.
	3: optional Types.TUniqueId registration_id;

	// Unique identifier for the statestore instance.
	4: optional Types.TUniqueId statestore_id;
	}

	struct TUpdateStateResponse {
	// Whether the call was executed correctly at the application level
	1: required Status.TStatus status;

	// List of updates published by the subscriber to be made centrally by the statestore
	2: required list<TTopicDelta> topic_updates;

	// True if this update was skipped by the subscriber. This is distinguished from a
	// non-OK status since the former indicates an error which contributes to the
	// statestore's view of a subscriber's liveness.
	3: optional bool skipped;
	}

	struct THeartbeatRequest {
	// Protocol version of the statestore
	1: optional StatestoreServiceVersion protocol_version =
	StatestoreServiceVersion.V2

	// registration_id of the receiver
	2: optional Types.TUniqueId registration_id;

	// Unique identifier for the statestore instance.
	3: optional Types.TUniqueId statestore_id;

	// Flag set by standby Statestore instance to request the connection state between
	// active statestore and the subscriber.
	4: optional bool request_statestore_conn_state;
	}

	struct THeartbeatResponse {
	// Whether the call was executed correctly at the application level
	1: required Status.TStatus status;

	// Connection state between active statestore and the subscriber reported by
	// the subscriber.
	2: optional TStatestoreConnState statestore_conn_state;
	}

	struct TUpdateCatalogdRequest {
	// Protocol version of the statestore
	1: required StatestoreServiceVersion protocol_version =
	StatestoreServiceVersion.V2

	// registration_id of the receiver
	2: required Types.TUniqueId registration_id;

	// Unique identifier for the statestore instance.
	3: required Types.TUniqueId statestore_id;

	// The version of active catalogd
	4: required i64 catalogd_version;

	// Catalog registration info.
	5: required TCatalogRegistration catalogd_registration;
	}

	struct TUpdateCatalogdResponse {
	// Whether the call was executed correctly at the application level
	1: required Status.TStatus status;

	// True if this update was skipped by the subscriber. This is distinguished from a
	// non-OK status since the former indicates an error which contributes to the
	// statestore's view of a subscriber's liveness.
	2: optional bool skipped;
	}

	struct TUpdateStatestoredRoleRequest {
	// Protocol version of the statestore
	1: required StatestoreServiceVersion protocol_version =
	StatestoreServiceVersion.V2;

	// registration_id of the receiver
	2: required Types.TUniqueId registration_id;

	// Unique identifier for the statestore instance.
	3: required Types.TUniqueId statestore_id;

	// Monotonously increasing number
	4: required i64 active_statestored_version;

	// Active state of Statestore instance
	5: required bool is_active;

	// Send elected active catalogd along with the role of active statestore.
	// The version of active catalogd. Don't set this catalogd_version and
	// catalogd_registration if active catalogd has not been elected.
	6: optional i64 catalogd_version;

	// Catalog registration info.
	7: optional TCatalogRegistration catalogd_registration;
	}

	struct TUpdateStatestoredRoleResponse {
	// Whether the call was executed correctly
	1: required Status.TStatus status;

	// True if this update was skipped by the subscriber.
	2: optional bool skipped;
	}

	service StatestoreSubscriber {
	// Called when the statestore sends a topic update. The request contains a map of
	// topic names to TTopicDelta updates, sent from the statestore to the subscriber. Each
	// of these delta updates will contain a list of additions to the topic and a list of
	// deletions from the topic.
	// In response, the subscriber returns an aggregated list of updates to topic(s) to
	// the statestore. Each update is a TTopicDelta that contains a list of additions to
	// the topic and a list of deletions from the topic. Additionally, if a subscriber has
	// received an unexpected delta update version range, they can request a new delta
	// update based off a specific version from the statestore. The next statestore
	// delta update will be based off of the version the subscriber requested.
	//
	// When Statestore HA is enabled, two statestore instances will be created in an Impala
	// cluster as Active-Passive HA pair. All subscribers should register to both
	// statestore instances so that two statestore instances have same set of subscribers.
	// Both Statestore instances send heartbeat to their subscribers, but only active
	// statestore instance sends topic update to its subscribers.
	TUpdateStateResponse UpdateState(1: TUpdateStateRequest params);

	// Called when the statestore sends a heartbeat.
	THeartbeatResponse Heartbeat(1: THeartbeatRequest params);

	// Called when active catalogd has been updated.
	TUpdateCatalogdResponse UpdateCatalogd(1: TUpdateCatalogdRequest params);

	// Called by standby statestore when the Statestore service failover happens, which
	// causes the active states of statestoreds are changed.
	TUpdateStatestoredRoleResponse UpdateStatestoredRole(
	1: TUpdateStatestoredRoleRequest params);
	}

	struct TStatestoreHaHandshakeRequest {
	// Service's version of source Statestore instance
	1: required StatestoreServiceVersion src_protocol_version =
	StatestoreServiceVersion.V2;

	// Instance id of source Statestore instance
	2: required Types.TUniqueId src_statestore_id;

	// Address of the Statestore that source statestore instance runs
	3: required string src_statestore_address;

	// True if starting flag statestore_force_active is set as true for source statestore
	// instance.
	4: required bool src_force_active;
	}

	struct TStatestoreHaHandshakeResponse {
	// Whether the call was executed correctly
	1: required Status.TStatus status;

	// Service's version of destination Statestore instance
	2: required StatestoreServiceVersion dst_protocol_version =
	StatestoreServiceVersion.V2;

	// Instance id of destination Statestore instance
	3: required Types.TUniqueId dst_statestore_id;

	// Indication if the destination Statestore is active for preemption. Source
	// statestore should set itself as inactive if dst_statestore_active is set as true.
	// Otherwise, source statestore sets itself as active.
	4: required bool dst_statestore_active;
	}

	struct TStatestoreHaHeartbeatRequest {
	// Service's version of source Statestore instance
	1: required StatestoreServiceVersion protocol_version =
	StatestoreServiceVersion.V2;

	// Destination Statestore instance id
	2: required Types.TUniqueId dst_statestore_id;

	// Source Statestore instance id
	3: required Types.TUniqueId src_statestore_id;
	}

	struct TStatestoreHaHeartbeatResponse {
	1: required Status.TStatus status;
	}

	// Service for communication between two statestore instances in an Active-Passive
	// HA (High Availability) pair.
	service StatestoreHaService {
	// StatestoreHaHandshake: negotiate active role between two instances during startup.
	TStatestoreHaHandshakeResponse StatestoreHaHandshake(
	1: TStatestoreHaHandshakeRequest params);

	// StatestoreHaHeartbeat: active statestore sends heartbeat to standby statestore.
	TStatestoreHaHeartbeatResponse StatestoreHaHeartbeat(
	1: TStatestoreHaHeartbeatRequest params);
	}