etcd/etcdserver/etcdserverpb/rpc.proto

syntax = "proto3";
package etcdserverpb;

import "gogoproto/gogo.proto";
import "etcd/storage/storagepb/kv.proto";

option (gogoproto.marshaler_all) = true;
option (gogoproto.unmarshaler_all) = true;

service KV {
  // Range gets the keys in the range from the store.
  rpc Range(RangeRequest) returns (RangeResponse) {}

  // Put puts the given key into the store.
  // A put request increases the revision of the store,
  // and generates one event in the event history.
  rpc Put(PutRequest) returns (PutResponse) {}

  // Delete deletes the given range from the store.
  // A delete request increase the revision of the store,
  // and generates one event in the event history.
  rpc DeleteRange(DeleteRangeRequest) returns (DeleteRangeResponse) {}

  // Txn processes all the requests in one transaction.
  // A txn request increases the revision of the store,
  // and generates events with the same revision in the event history.
  // It is not allowed to modify the same key several times within one txn.
  rpc Txn(TxnRequest) returns (TxnResponse) {}

  // Compact compacts the event history in etcd. User should compact the
  // event history periodically, or it will grow infinitely.
  rpc Compact(CompactionRequest) returns (CompactionResponse) {}
}

service Watch {
  // Watch watches the events happening or happened. Both input and output
  // are stream. One watch rpc can watch for multiple keys or prefixs and
  // get a stream of events. The whole events history can be watched unless
  // compacted.
  rpc Watch(stream WatchRequest) returns (stream WatchResponse) {}
}

service Lease {
  // LeaseCreate creates a lease. A lease has a TTL. The lease will expire if the
  // server does not receive a keepAlive within TTL from the lease holder.
  // All keys attached to the lease will be expired and deleted if the lease expires.
  // The key expiration generates an event in event history.
  rpc LeaseCreate(LeaseCreateRequest) returns (LeaseCreateResponse) {}

  // LeaseRevoke revokes a lease. All the key attached to the lease will be expired and deleted.
  rpc LeaseRevoke(LeaseRevokeRequest) returns (LeaseRevokeResponse) {}

  // KeepAlive keeps the lease alive.
  rpc LeaseKeepAlive(stream LeaseKeepAliveRequest) returns (stream LeaseKeepAliveResponse) {}

  // TODO(xiangli) List all existing Leases?
  // TODO(xiangli) Get details information (expirations, leased keys, etc.) of a lease?
}

message ResponseHeader {
  uint64 cluster_id = 1;
  uint64 member_id = 2;
  // revision of the store when the request was applied.
  int64 revision = 3;
  // term of raft when the request was applied.
  uint64 raft_term = 4;
}

message RangeRequest {
  // if the range_end is not given, the request returns the key.
  bytes key = 1;
  // if the range_end is given, it gets the keys in range [key, range_end).
  bytes range_end = 2;
  // limit the number of keys returned.
  int64 limit = 3;
  // range over the store at the given revision.
  // if revision is less or equal to zero, range over the newest store.
  // if the revision has been compacted, ErrCompaction will be returned in
  // response.
  int64 revision = 4;
}

message RangeResponse {
  ResponseHeader header = 1;
  repeated storagepb.KeyValue kvs = 2;
  // more indicates if there are more keys to return in the requested range.
  bool more = 3;
}

message PutRequest {
  bytes key = 1;
  bytes value = 2;
  int64 lease = 3;
}

message PutResponse {
  ResponseHeader header = 1;
}

message DeleteRangeRequest {
  // if the range_end is not given, the request deletes the key.
  bytes key = 1;
  // if the range_end is given, it deletes the keys in range [key, range_end).
  bytes range_end = 2;
}

message DeleteRangeResponse {
  ResponseHeader header = 1;
}

message RequestUnion {
  oneof request {
    RangeRequest request_range = 1;
    PutRequest request_put = 2;
    DeleteRangeRequest request_delete_range = 3;
  }
}

message ResponseUnion {
  oneof response {
    RangeResponse response_range = 1;
    PutResponse response_put = 2;
    DeleteRangeResponse response_delete_range = 3;
  }
}

message Compare {
  enum CompareResult {
    EQUAL = 0;
    GREATER = 1;
    LESS = 2;
  }
  enum CompareTarget {
    VERSION = 0;
    CREATE = 1;
    MOD = 2;
    VALUE= 3;
  }
  CompareResult result = 1;
  CompareTarget target = 2;
  // key path
  bytes key = 3;
  oneof target_union {
    // version of the given key
    int64 version = 4;
    // create revision of the given key
    int64 create_revision = 5;
    // last modified revision of the given key
    int64 mod_revision = 6;
    // value of the given key
    bytes value = 7;
  }
}

// If the comparisons succeed, then the success requests will be processed in order,
// and the response will contain their respective responses in order.
// If the comparisons fail, then the failure requests will be processed in order,
// and the response will contain their respective responses in order.

// From google paxosdb paper:
// Our implementation hinges around a powerful primitive which we call MultiOp. All other database
// operations except for iteration are implemented as a single call to MultiOp. A MultiOp is applied atomically
// and consists of three components:
// 1. A list of tests called guard. Each test in guard checks a single entry in the database. It may check
// for the absence or presence of a value, or compare with a given value. Two different tests in the guard
// may apply to the same or different entries in the database. All tests in the guard are applied and
// MultiOp returns the results. If all tests are true, MultiOp executes t op (see item 2 below), otherwise
// it executes f op (see item 3 below).
// 2. A list of database operations called t op. Each operation in the list is either an insert, delete, or
// lookup operation, and applies to a single database entry. Two different operations in the list may apply
// to the same or different entries in the database. These operations are executed
// if guard evaluates to
// true.
// 3. A list of database operations called f op. Like t op, but executed if guard evaluates to false.
message TxnRequest {
  repeated Compare compare = 1;
  repeated RequestUnion success = 2;
  repeated RequestUnion failure = 3;
}

message TxnResponse {
  ResponseHeader header = 1;
  bool succeeded = 2;
  repeated ResponseUnion responses = 3;
}

// Compaction compacts the kv store upto the given revision (including).
// It removes the old versions of a key. It keeps the newest version of
// the key even if its latest modification revision is smaller than the given
// revision.
message CompactionRequest {
  int64 revision = 1;
}

message CompactionResponse {
  ResponseHeader header = 1;
}

message WatchRequest {
  oneof request_union {
    WatchCreateRequest create_request = 1;
    WatchCancelRequest cancel_request = 2;
  }
}

message WatchCreateRequest {
  // the key to be watched
  bytes key = 1;
  // the prefix to be watched.
  bytes prefix = 2;
  // start_revision is an optional revision (including) to watch from. No start_revision is "now".
  int64 start_revision = 3;
  // TODO: support Range watch?
}

message WatchCancelRequest {
  int64 watch_id = 1;
}

message WatchResponse {
  ResponseHeader header = 1;
  // watch_id is the ID of the watching the response sent to.
  int64 watch_id = 2;
  // If the response is for a create watch request, created is set to true.
  // Client should record the watch_id and prepare for receiving events for
  // that watching from the same stream.
  // All events sent to the created watching will attach with the same watch_id.
  bool created = 3;
  // If the response is for a cancel watch request, cancel is set to true.
  // No further events will be sent to the canceled watching.
  bool canceled = 4;
  // If a watching tries to watch at a compacted index, compacted will be set to true.
  //
  // This happens when creating a watching at a compacted revision or the watching cannot
  // catch up with the progress of the KV.
  //
  // Client should treat the watching as canceled and should not try to create any
  // watching with same start_revision again.
  bool compacted = 5;

  repeated storagepb.Event events = 11;
}

message LeaseCreateRequest {
  // advisory ttl in seconds
  int64 TTL = 1;
}

message LeaseCreateResponse {
  ResponseHeader header = 1;
  int64 ID = 2;
  // server decided ttl in second
  int64 TTL = 3;
  string error = 4;
}

message LeaseRevokeRequest {
  int64 ID = 1;
}

message LeaseRevokeResponse {
  ResponseHeader header = 1;
}

message LeaseKeepAliveRequest {
  int64 ID = 1;
}

message LeaseKeepAliveResponse {
  ResponseHeader header = 1;
  int64 TTL = 2;
}