diff --git a/CHANGELOG.md b/CHANGELOG.md new file mode 100644 --- /dev/null +++ b/CHANGELOG.md diff --git a/LICENSE b/LICENSE new file mode 100644 --- /dev/null +++ b/LICENSE @@ -0,0 +1,373 @@ +Mozilla Public License Version 2.0 +================================== + +1. Definitions +-------------- + +1.1. "Contributor" + means each individual or legal entity that creates, contributes to + the creation of, or owns Covered Software. + +1.2. "Contributor Version" + means the combination of the Contributions of others (if any) used + by a Contributor and that particular Contributor's Contribution. + +1.3. "Contribution" + means Covered Software of a particular Contributor. + +1.4. "Covered Software" + means Source Code Form to which the initial Contributor has attached + the notice in Exhibit A, the Executable Form of such Source Code + Form, and Modifications of such Source Code Form, in each case + including portions thereof. + +1.5. "Incompatible With Secondary Licenses" + means + + (a) that the initial Contributor has attached the notice described + in Exhibit B to the Covered Software; or + + (b) that the Covered Software was made available under the terms of + version 1.1 or earlier of the License, but not also under the + terms of a Secondary License. + +1.6. "Executable Form" + means any form of the work other than Source Code Form. + +1.7. "Larger Work" + means a work that combines Covered Software with other material, in + a separate file or files, that is not Covered Software. + +1.8. "License" + means this document. + +1.9. "Licensable" + means having the right to grant, to the maximum extent possible, + whether at the time of the initial grant or subsequently, any and + all of the rights conveyed by this License. + +1.10. "Modifications" + means any of the following: + + (a) any file in Source Code Form that results from an addition to, + deletion from, or modification of the contents of Covered + Software; or + + (b) any new file in Source Code Form that contains any Covered + Software. + +1.11. "Patent Claims" of a Contributor + means any patent claim(s), including without limitation, method, + process, and apparatus claims, in any patent Licensable by such + Contributor that would be infringed, but for the grant of the + License, by the making, using, selling, offering for sale, having + made, import, or transfer of either its Contributions or its + Contributor Version. + +1.12. "Secondary License" + means either the GNU General Public License, Version 2.0, the GNU + Lesser General Public License, Version 2.1, the GNU Affero General + Public License, Version 3.0, or any later versions of those + licenses. + +1.13. "Source Code Form" + means the form of the work preferred for making modifications. + +1.14. "You" (or "Your") + means an individual or a legal entity exercising rights under this + License. For legal entities, "You" includes any entity that + controls, is controlled by, or is under common control with You. For + purposes of this definition, "control" means (a) the power, direct + or indirect, to cause the direction or management of such entity, + whether by contract or otherwise, or (b) ownership of more than + fifty percent (50%) of the outstanding shares or beneficial + ownership of such entity. + +2. License Grants and Conditions +-------------------------------- + +2.1. Grants + +Each Contributor hereby grants You a world-wide, royalty-free, +non-exclusive license: + +(a) under intellectual property rights (other than patent or trademark) + Licensable by such Contributor to use, reproduce, make available, + modify, display, perform, distribute, and otherwise exploit its + Contributions, either on an unmodified basis, with Modifications, or + as part of a Larger Work; and + +(b) under Patent Claims of such Contributor to make, use, sell, offer + for sale, have made, import, and otherwise transfer either its + Contributions or its Contributor Version. + +2.2. Effective Date + +The licenses granted in Section 2.1 with respect to any Contribution +become effective for each Contribution on the date the Contributor first +distributes such Contribution. + +2.3. Limitations on Grant Scope + +The licenses granted in this Section 2 are the only rights granted under +this License. No additional rights or licenses will be implied from the +distribution or licensing of Covered Software under this License. +Notwithstanding Section 2.1(b) above, no patent license is granted by a +Contributor: + +(a) for any code that a Contributor has removed from Covered Software; + or + +(b) for infringements caused by: (i) Your and any other third party's + modifications of Covered Software, or (ii) the combination of its + Contributions with other software (except as part of its Contributor + Version); or + +(c) under Patent Claims infringed by Covered Software in the absence of + its Contributions. + +This License does not grant any rights in the trademarks, service marks, +or logos of any Contributor (except as may be necessary to comply with +the notice requirements in Section 3.4). + +2.4. Subsequent Licenses + +No Contributor makes additional grants as a result of Your choice to +distribute the Covered Software under a subsequent version of this +License (see Section 10.2) or under the terms of a Secondary License (if +permitted under the terms of Section 3.3). + +2.5. Representation + +Each Contributor represents that the Contributor believes its +Contributions are its original creation(s) or it has sufficient rights +to grant the rights to its Contributions conveyed by this License. + +2.6. Fair Use + +This License is not intended to limit any rights You have under +applicable copyright doctrines of fair use, fair dealing, or other +equivalents. + +2.7. Conditions + +Sections 3.1, 3.2, 3.3, and 3.4 are conditions of the licenses granted +in Section 2.1. + +3. Responsibilities +------------------- + +3.1. Distribution of Source Form + +All distribution of Covered Software in Source Code Form, including any +Modifications that You create or to which You contribute, must be under +the terms of this License. You must inform recipients that the Source +Code Form of the Covered Software is governed by the terms of this +License, and how they can obtain a copy of this License. You may not +attempt to alter or restrict the recipients' rights in the Source Code +Form. + +3.2. Distribution of Executable Form + +If You distribute Covered Software in Executable Form then: + +(a) such Covered Software must also be made available in Source Code + Form, as described in Section 3.1, and You must inform recipients of + the Executable Form how they can obtain a copy of such Source Code + Form by reasonable means in a timely manner, at a charge no more + than the cost of distribution to the recipient; and + +(b) You may distribute such Executable Form under the terms of this + License, or sublicense it under different terms, provided that the + license for the Executable Form does not attempt to limit or alter + the recipients' rights in the Source Code Form under this License. + +3.3. Distribution of a Larger Work + +You may create and distribute a Larger Work under terms of Your choice, +provided that You also comply with the requirements of this License for +the Covered Software. If the Larger Work is a combination of Covered +Software with a work governed by one or more Secondary Licenses, and the +Covered Software is not Incompatible With Secondary Licenses, this +License permits You to additionally distribute such Covered Software +under the terms of such Secondary License(s), so that the recipient of +the Larger Work may, at their option, further distribute the Covered +Software under the terms of either this License or such Secondary +License(s). + +3.4. Notices + +You may not remove or alter the substance of any license notices +(including copyright notices, patent notices, disclaimers of warranty, +or limitations of liability) contained within the Source Code Form of +the Covered Software, except that You may alter any license notices to +the extent required to remedy known factual inaccuracies. + +3.5. Application of Additional Terms + +You may choose to offer, and to charge a fee for, warranty, support, +indemnity or liability obligations to one or more recipients of Covered +Software. However, You may do so only on Your own behalf, and not on +behalf of any Contributor. You must make it absolutely clear that any +such warranty, support, indemnity, or liability obligation is offered by +You alone, and You hereby agree to indemnify every Contributor for any +liability incurred by such Contributor as a result of warranty, support, +indemnity or liability terms You offer. You may include additional +disclaimers of warranty and limitations of liability specific to any +jurisdiction. + +4. Inability to Comply Due to Statute or Regulation +--------------------------------------------------- + +If it is impossible for You to comply with any of the terms of this +License with respect to some or all of the Covered Software due to +statute, judicial order, or regulation then You must: (a) comply with +the terms of this License to the maximum extent possible; and (b) +describe the limitations and the code they affect. Such description must +be placed in a text file included with all distributions of the Covered +Software under this License. Except to the extent prohibited by statute +or regulation, such description must be sufficiently detailed for a +recipient of ordinary skill to be able to understand it. + +5. Termination +-------------- + +5.1. The rights granted under this License will terminate automatically +if You fail to comply with any of its terms. However, if You become +compliant, then the rights granted under this License from a particular +Contributor are reinstated (a) provisionally, unless and until such +Contributor explicitly and finally terminates Your grants, and (b) on an +ongoing basis, if such Contributor fails to notify You of the +non-compliance by some reasonable means prior to 60 days after You have +come back into compliance. Moreover, Your grants from a particular +Contributor are reinstated on an ongoing basis if such Contributor +notifies You of the non-compliance by some reasonable means, this is the +first time You have received notice of non-compliance with this License +from such Contributor, and You become compliant prior to 30 days after +Your receipt of the notice. + +5.2. If You initiate litigation against any entity by asserting a patent +infringement claim (excluding declaratory judgment actions, +counter-claims, and cross-claims) alleging that a Contributor Version +directly or indirectly infringes any patent, then the rights granted to +You by any and all Contributors for the Covered Software under Section +2.1 of this License shall terminate. + +5.3. In the event of termination under Sections 5.1 or 5.2 above, all +end user license agreements (excluding distributors and resellers) which +have been validly granted by You or Your distributors under this License +prior to termination shall survive termination. + +************************************************************************ +* * +* 6. Disclaimer of Warranty * +* ------------------------- * +* * +* Covered Software is provided under this License on an "as is" * +* basis, without warranty of any kind, either expressed, implied, or * +* statutory, including, without limitation, warranties that the * +* Covered Software is free of defects, merchantable, fit for a * +* particular purpose or non-infringing. The entire risk as to the * +* quality and performance of the Covered Software is with You. * +* Should any Covered Software prove defective in any respect, You * +* (not any Contributor) assume the cost of any necessary servicing, * +* repair, or correction. This disclaimer of warranty constitutes an * +* essential part of this License. No use of any Covered Software is * +* authorized under this License except under this disclaimer. * +* * +************************************************************************ + +************************************************************************ +* * +* 7. Limitation of Liability * +* -------------------------- * +* * +* Under no circumstances and under no legal theory, whether tort * +* (including negligence), contract, or otherwise, shall any * +* Contributor, or anyone who distributes Covered Software as * +* permitted above, be liable to You for any direct, indirect, * +* special, incidental, or consequential damages of any character * +* including, without limitation, damages for lost profits, loss of * +* goodwill, work stoppage, computer failure or malfunction, or any * +* and all other commercial damages or losses, even if such party * +* shall have been informed of the possibility of such damages. This * +* limitation of liability shall not apply to liability for death or * +* personal injury resulting from such party's negligence to the * +* extent applicable law prohibits such limitation. Some * +* jurisdictions do not allow the exclusion or limitation of * +* incidental or consequential damages, so this exclusion and * +* limitation may not apply to You. * +* * +************************************************************************ + +8. Litigation +------------- + +Any litigation relating to this License may be brought only in the +courts of a jurisdiction where the defendant maintains its principal +place of business and such litigation shall be governed by laws of that +jurisdiction, without reference to its conflict-of-law provisions. +Nothing in this Section shall prevent a party's ability to bring +cross-claims or counter-claims. + +9. Miscellaneous +---------------- + +This License represents the complete agreement concerning the subject +matter hereof. If any provision of this License is held to be +unenforceable, such provision shall be reformed only to the extent +necessary to make it enforceable. Any law or regulation which provides +that the language of a contract shall be construed against the drafter +shall not be used to construe this License against a Contributor. + +10. Versions of the License +--------------------------- + +10.1. New Versions + +Mozilla Foundation is the license steward. Except as provided in Section +10.3, no one other than the license steward has the right to modify or +publish new versions of this License. Each version will be given a +distinguishing version number. + +10.2. Effect of New Versions + +You may distribute the Covered Software under the terms of the version +of the License under which You originally received the Covered Software, +or under the terms of any subsequent version published by the license +steward. + +10.3. Modified Versions + +If you create software not governed by this License, and you want to +create a new license for such software, you may create and use a +modified version of this License if you rename the license and remove +any references to the name of the license steward (except to note that +such modified license differs from this License). + +10.4. Distributing Source Code Form that is Incompatible With Secondary +Licenses + +If You choose to distribute Source Code Form that is Incompatible With +Secondary Licenses under the terms of this version of the License, the +notice described in Exhibit B of this License must be attached. + +Exhibit A - Source Code Form License Notice +------------------------------------------- + + This Source Code Form is subject to the terms of the Mozilla Public + License, v. 2.0. If a copy of the MPL was not distributed with this + file, You can obtain one at http://mozilla.org/MPL/2.0/. + +If it is not possible or desirable to put the notice in a particular +file, then You may include the notice in a location (such as a LICENSE +file in a relevant directory) where a recipient would be likely to look +for such a notice. + +You may add additional accurate notices of copyright ownership. + +Exhibit B - "Incompatible With Secondary Licenses" Notice +--------------------------------------------------------- + + This Source Code Form is "Incompatible With Secondary Licenses", as + defined by the Mozilla Public License, v. 2.0. diff --git a/Setup.hs b/Setup.hs new file mode 100644 --- /dev/null +++ b/Setup.hs @@ -0,0 +1,6 @@ +-- import Distribution.Simple +-- main = defaultMain + +import Data.ProtoLens.Setup + +main = defaultMainGeneratingProtos "proto" diff --git a/flink-statefulfun.cabal b/flink-statefulfun.cabal new file mode 100644 --- /dev/null +++ b/flink-statefulfun.cabal @@ -0,0 +1,74 @@ +cabal-version: 2.4 +-- Initial package description 'policy.cabal' generated by 'cabal init'. +-- For further documentation, see http://haskell.org/cabal/users-guide/ + +name: flink-statefulfun +version: 0.1.0.0 +synopsis: Flink stateful functions SDK +description: + Typeclasses for serving Flink stateful functions + from Haskell. +-- bug-reports: +license: MPL-2.0 +license-file: LICENSE +author: Timothy Bess +maintainer: tdbgamer@gmail.com +-- copyright: +-- category: + +-- build-type: Simple +build-type: Custom + +extra-source-files: CHANGELOG.md + proto/**/*.proto + +custom-setup + setup-depends: base, Cabal, proto-lens-setup + +library + ghc-options: -Wall + build-tool-depends: proto-lens-protoc:proto-lens-protoc + hs-source-dirs: src + autogen-modules: Proto.RequestReply Proto.RequestReply_Fields + Proto.Kafka Proto.Kafka_Fields + other-modules: Network.Flink.ProtoServant + exposed-modules: Network.Flink.Stateful + Proto.RequestReply Proto.RequestReply_Fields + Proto.Kafka Proto.Kafka_Fields + -- exposed-modules: + -- other-extensions: + build-depends: base >= 4.0 && < 4.15 + , text >= 1.0 && < 1.3 + , bytestring >= 0.10 && < 0.11 + , either >= 5 && < 5.1 + , containers >= 0.5 && < 0.7 + , wai >= 3 && < 3.3 + , warp >= 3 && < 3.4 + , http-types >= 0.10 && < 0.13 + , http-media >= 0.7 && < 0.9 + , mtl >= 2 && < 2.3 + , lens-family >= 2 && < 2.2 + , proto-lens >= 0.5 && < 0.8 + , proto-lens-runtime >= 0.5 && < 0.8 + , proto-lens-protobuf-types >= 0.5 && < 0.8 + , servant >= 0.16 && < 0.19 + , servant-server >= 0.16 && < 0.19 + + default-extensions: OverloadedStrings + QuasiQuotes + StrictData + GeneralizedNewtypeDeriving + FlexibleContexts + FlexibleInstances + LambdaCase + TupleSections + DataKinds + TypeOperators + DeriveGeneric + DeriveFunctor + ExistentialQuantification + MultiParamTypeClasses + FunctionalDependencies + ConstraintKinds + + default-language: Haskell2010 diff --git a/proto/Example.proto b/proto/Example.proto new file mode 100644 --- /dev/null +++ b/proto/Example.proto @@ -0,0 +1,11 @@ +syntax = "proto3"; + +package example; + +message GreeterRequest { + string name = 1; +} + +message GreeterResponse { + string greeting = 1; +} diff --git a/proto/Kafka.proto b/proto/Kafka.proto new file mode 100644 --- /dev/null +++ b/proto/Kafka.proto @@ -0,0 +1,29 @@ +/* + * 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. + */ + +syntax = "proto3"; + +package org.apache.flink.statefun.flink.io; +option java_package = "org.apache.flink.statefun.flink.io.generated"; +option java_multiple_files = true; + +message KafkaProducerRecord { + string key = 1; + bytes value_bytes = 2; + string topic = 3; +} diff --git a/proto/RequestReply.proto b/proto/RequestReply.proto new file mode 100644 --- /dev/null +++ b/proto/RequestReply.proto @@ -0,0 +1,145 @@ +/* + * 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. + */ + +syntax = "proto3"; + +package org.apache.flink.statefun.flink.core.polyglot; +option java_package = "org.apache.flink.statefun.flink.core.polyglot.generated"; +option java_multiple_files = true; + +import "google/protobuf/any.proto"; + +// ------------------------------------------------------------------------------------------------------------------- +// Common message definitions +// ------------------------------------------------------------------------------------------------------------------- + +// An Address is the unique identity of an individual StatefulFunction, containing +// a function's type and an unique identifier within the type. The function's +// type denotes the "class" of function to invoke, while the unique identifier addresses the +// invocation to a specific function instance. +message Address { + string namespace = 1; + string type = 2; + string id = 3; +} + +// ------------------------------------------------------------------------------------------------------------------- +// Messages sent to a Remote Function +// ------------------------------------------------------------------------------------------------------------------- + +// The following section contains all the message types that are sent +// from Flink to a remote function. +message ToFunction { + // PersistedValue represents a PersistedValue's value that is managed by Flink on behalf of a remote function. + message PersistedValue { + // The unique name of the persisted state. + string state_name = 1; + // The serialized state value + bytes state_value = 2; + } + + // Invocation represents a remote function call, it associated with an (optional) return address, + // and an argument. + message Invocation { + // The address of the function that requested the invocation (possibly absent) + Address caller = 1; + // The invocation argument (aka the message sent to the target function) + google.protobuf.Any argument = 2; + } + + // InvocationBatchRequest represents a request to invoke a remote function. It is always associated with a target + // address (the function to invoke), a list of eager state values. + message InvocationBatchRequest { + // The address of the function to invoke + Address target = 1; + // A list of PersistedValues that were registered as an eager state. + repeated PersistedValue state = 2; + // A non empty (at least one) list of invocations + repeated Invocation invocations = 3; + } + + oneof request { + InvocationBatchRequest invocation = 100; + } +} + +// ------------------------------------------------------------------------------------------------------------------- +// Messages sent from a Remote Function +// ------------------------------------------------------------------------------------------------------------------- + +// The following section contains messages sent from a remote function back to Flink. +message FromFunction { + // MutatePersistedValueCommand represents a command sent from a remote function to Flink, + // requesting a change to a persisted value. + message PersistedValueMutation { + enum MutationType { + DELETE = 0; + MODIFY = 1; + } + MutationType mutation_type = 1; + string state_name = 2; + bytes state_value = 3; + } + + // Invocation represents a remote function call, it associated with a (mandatory) target address, + // and an argument. + message Invocation { + // The target function to invoke + Address target = 1; + // The invocation argument (aka the message sent to the target function) + google.protobuf.Any argument = 2; + } + + // DelayedInvocation represents a delayed remote function call with a target address, an argument + // and a delay in milliseconds, after which this message to be sent. + message DelayedInvocation { + // the amount of milliseconds to wait before sending this message + int64 delay_in_ms = 1; + // the target address to send this message to + Address target = 2; + // the invocation argument + google.protobuf.Any argument = 3; + } + + // EgressMessage an argument to forward to an egress. + // An egress is identified by a namespace and type (see EgressIdentifier SDK class). + // The argument is a google.protobuf.Any + message EgressMessage { + // The target egress namespace + string egress_namespace = 1; + // The target egress type + string egress_type = 2; + // egress argument + google.protobuf.Any argument = 3; + } + + // InvocationResponse represents a result of an org.apache.flink.statefun.flink.core.polyglot.ToFunction.InvocationBatchRequest + // it contains a list of state mutation to preform as a result of computing this batch, and a list of outgoing messages. + message InvocationResponse { + repeated PersistedValueMutation state_mutations = 1; + repeated Invocation outgoing_messages = 2; + repeated DelayedInvocation delayed_invocations = 3; + repeated EgressMessage outgoing_egresses = 4; + } + + oneof response { + InvocationResponse invocation_result = 100; + } +} + + diff --git a/src/Network/Flink/ProtoServant.hs b/src/Network/Flink/ProtoServant.hs new file mode 100644 --- /dev/null +++ b/src/Network/Flink/ProtoServant.hs @@ -0,0 +1,24 @@ +module Network.Flink.ProtoServant where + +import qualified Data.ByteString.Lazy as BS +import qualified Data.List.NonEmpty as NE +import qualified Data.ProtoLens as P +import Network.HTTP.Media ((//)) +import qualified Servant.API.ContentTypes as S + +data Proto + +instance S.Accept Proto where + contentTypes _ = + NE.fromList + [ "application" // "octet-stream", + "application" // "protobuf", + "application" // "x-protobuf", + "application" // "vnd.google.protobuf" + ] + +instance P.Message m => S.MimeRender Proto m where + mimeRender _ = BS.fromStrict . P.encodeMessage + +instance P.Message m => S.MimeUnrender Proto m where + mimeUnrender _ = P.decodeMessage . BS.toStrict diff --git a/src/Network/Flink/Stateful.hs b/src/Network/Flink/Stateful.hs new file mode 100644 --- /dev/null +++ b/src/Network/Flink/Stateful.hs @@ -0,0 +1,315 @@ +module Network.Flink.Stateful + ( StatefulFunc + ( insideCtx, + getCtx, + setCtx, + modifyCtx, + sendMsg, + sendMsgDelay, + sendEgressMsg + ), + makeConcrete, + createApp, + flinkServer, + flinkApi, + kafkaRecord, + Function, + FlinkState (..), + FunctionTable + ) +where + +import Control.Monad.Except +import Control.Monad.Reader +import Control.Monad.State (MonadState, StateT (..), gets, modify) +import Data.ByteString (ByteString) +import qualified Data.ByteString.Lazy.Char8 as BSL +import Data.Either.Combinators (mapLeft) +import Data.Foldable (Foldable (toList)) +import Data.Map (Map) +import qualified Data.Map as Map +import Data.Maybe (listToMaybe) +import Data.ProtoLens (Message, defMessage, encodeMessage) +import Data.ProtoLens.Any (UnpackError) +import qualified Data.ProtoLens.Any as Any +import Data.ProtoLens.Prism +import Data.Sequence (Seq) +import qualified Data.Sequence as Seq +import Data.Text (Text) +import Data.Text.Lazy (fromStrict) +import qualified Data.Text.Lazy.Encoding as T +import Lens.Family2 +import Network.Flink.ProtoServant (Proto) +import Proto.Google.Protobuf.Any (Any) +import qualified Proto.Kafka as Kafka +import qualified Proto.Kafka_Fields as Kafka +import Proto.RequestReply (FromFunction, ToFunction) +import qualified Proto.RequestReply as PR +import qualified Proto.RequestReply_Fields as PR +import Servant + +--- | Table of stateful functions `(functionNamespace, functionType) -> (initialState, function) +type FunctionTable = Map (Text, Text) (ByteString, ByteString -> Env -> PR.ToFunction'InvocationBatchRequest -> IO (Either FlinkError (FunctionState ByteString))) + +data Env = Env + { envFunctionNamespace :: Text, + envFunctionType :: Text, + envFunctionId :: Text + } + deriving (Show) + +data FunctionState ctx = FunctionState + { functionStateCtx :: ctx, + functionStateMutated :: Bool, + functionStateInvocations :: Seq PR.FromFunction'Invocation, + functionStateDelayedInvocations :: Seq PR.FromFunction'DelayedInvocation, + functionStateEgressMessages :: Seq PR.FromFunction'EgressMessage + } + deriving (Show, Functor) + +newState :: a -> FunctionState a +newState initialCtx = FunctionState initialCtx False mempty mempty mempty + +-- | Monad stack used for the execution of a Flink stateful function +-- Don't reference this directly in your code if possible +newtype Function s a = Function {runFunction :: ExceptT FlinkError (StateT (FunctionState s) (ReaderT Env IO)) a} + deriving (Monad, Applicative, Functor, MonadState (FunctionState s), MonadError FlinkError, MonadIO, MonadReader Env) + +-- | Provides functions for Flink state SerDe +class FlinkState s where + -- | decodes Flink state types from strict 'ByteString's + decodeState :: ByteString -> Either String s + -- | encodes Flink state types to strict 'ByteString's + encodeState :: s -> ByteString + +instance FlinkState () where + decodeState _ = pure () + encodeState _ = "" + +{-| Used to represent all Flink stateful function capabilities. + +Contexts are received from Flink and deserialized into `s` +all modifications to state are shipped back to Flink at the end of the +batch to be persisted. + +Message passing is also queued up and passed back at the end of the current +batch. + +Example of a stateless function (done by setting `s` to `()`) that adds one +to a number and puts the protobuf response on Kafka via an egress message: + +@ +adder :: StatefulFunc () m => AdderRequest -> m () +adder msg = sendEgressMsg ("adder", "added") (kafkaRecord "added" name added) + where + num = msg ^. AdderRequest.num + added = defMessage & AdderResponse.num .~ (num + 1) +@ + +Example of a stateful function: + +@ +newtype GreeterState = GreeterState + { greeterStateCount :: Int + } + deriving (Generic, Show, ToJSON, FromJSON) + +instance FlinkState GreeterState where + decodeState = eitherDecode . BSL.fromStrict + encodeState = BSL.toStrict . Data.Aeson.encode + +counter :: StatefulFunc GreeterState m => EX.GreeterRequest -> m () +counter msg = do + newCount \<\- (+ 1) \<$> insideCtx greeterStateCount + let respMsg = "Saw " <> T.unpack name <> " " <> show newCount <> " time(s)" + + sendEgressMsg ("greeting", "greets") (kafkaRecord "greets" name $ response (T.pack respMsg)) + modifyCtx (\old -> old {greeterStateCount = newCount}) + where + name = msg ^. EX.name + response :: Text -> EX.GreeterResponse + response greeting = + defMessage + & EX.greeting .~ greeting +@ + +This will respond to each event by counting how many times it has been called for the name it was passed. +The final state is taken and sent back to Flink. Failures of any kind will cause state to rollback to +previous values seamlessly without double counting. +-} +class MonadIO m => StatefulFunc s m | m -> s where + -- Internal + setInitialCtx :: s -> m () + + -- Public + insideCtx :: (s -> a) -> m a + getCtx :: m s + setCtx :: s -> m () + modifyCtx :: (s -> s) -> m () + sendMsg :: + Message a => + -- | Function address (namespace, type, id) + (Text, Text, Text) -> + -- | protobuf message to send + a -> + m () + sendMsgDelay :: + Message a => + -- | Function address (namespace, type, id) + (Text, Text, Text) -> + -- | delay before message send + Int -> + -- | protobuf message to send + a -> + m () + sendEgressMsg :: + Message a => + -- | egress address (namespace, type) + (Text, Text) -> + -- | protobuf message to send (should be a Kafka or Kinesis protobuf record) + a -> + m () + +instance (FlinkState s) => StatefulFunc s (Function s) where + setInitialCtx ctx = modify (\old -> old {functionStateCtx = ctx}) + + insideCtx func = func <$> getCtx + getCtx = gets functionStateCtx + setCtx new = modify (\old -> old {functionStateCtx = new, functionStateMutated = True}) + modifyCtx mutator = mutator <$> getCtx >>= setCtx + sendMsg (namespace, funcType, id') msg = do + invocations <- gets functionStateInvocations + modify (\old -> old {functionStateInvocations = invocations Seq.:|> invocation}) + where + target :: PR.Address + target = + defMessage + & PR.namespace .~ namespace + & PR.type' .~ funcType + & PR.id .~ id' + invocation :: PR.FromFunction'Invocation + invocation = + defMessage + & PR.target .~ target + & PR.argument .~ Any.pack msg + sendMsgDelay (namespace, funcType, id') delay msg = do + invocations <- gets functionStateDelayedInvocations + modify (\old -> old {functionStateDelayedInvocations = invocations Seq.:|> invocation}) + where + target :: PR.Address + target = + defMessage + & PR.namespace .~ namespace + & PR.type' .~ funcType + & PR.id .~ id' + invocation :: PR.FromFunction'DelayedInvocation + invocation = + defMessage + & PR.delayInMs .~ fromIntegral delay + & PR.target .~ target + & PR.argument .~ Any.pack msg + sendEgressMsg (namespace, egressType) msg = do + egresses <- gets functionStateEgressMessages + modify (\old -> old {functionStateEgressMessages = egresses Seq.:|> egressMsg}) + where + egressMsg :: PR.FromFunction'EgressMessage + egressMsg = + defMessage + & PR.egressNamespace .~ namespace + & PR.egressType .~ egressType + & PR.argument .~ Any.pack msg + +data FlinkError + = MissingInvocationBatch + | ProtoUnpackError UnpackError + | ProtoDeserializeError String + | StateDecodeError String + | NoSuchFunction (Text, Text) + deriving (Show, Eq) + +invoke :: (FlinkState s, StatefulFunc s m, MonadError FlinkError m, Message a, MonadReader Env m) => (a -> m b) -> Any -> m b +invoke f input = f =<< liftEither (mapLeft ProtoUnpackError $ Any.unpack input) + +-- | Takes a function taking an abstract state/message type and converts it to take concrete 'ByteString's +-- This allows each function in the 'FunctionTable' to take its own individual type of state and just expose +-- a function accepting 'ByteString' to the library code. +makeConcrete :: (FlinkState s, Message a) => (a -> Function s ()) -> ByteString -> Env -> PR.ToFunction'InvocationBatchRequest -> IO (Either FlinkError (FunctionState ByteString)) +makeConcrete func initialContext env invocationBatch = runExceptT $ do + deserializedContext <- liftEither $ mapLeft StateDecodeError $ decodeState initialContext + (err, finalState) <- liftIO $ runner (newState deserializedContext) + liftEither err + return $ encodeState <$> finalState + where + runner state = runReaderT (runStateT (runExceptT $ runFunction runWithCtx) state) env + runWithCtx = do + defaultCtx <- gets functionStateCtx + let initialCtx = getInitialCtx defaultCtx (listToMaybe $ invocationBatch ^. PR.state) + case initialCtx of + Left err -> throwError err + Right ctx -> setInitialCtx ctx + mapM_ (invoke func) ((^. PR.argument) <$> invocationBatch ^. PR.invocations) + + getInitialCtx def pv = handleEmptyState def $ (^. PR.stateValue) <$> pv + handleEmptyState def state' = case state' of + Just "" -> return def + Just other -> mapLeft StateDecodeError $ decodeState other + Nothing -> return def + +createFlinkResp :: FunctionState ByteString -> FromFunction +createFlinkResp (FunctionState state mutated invocations delayedInvocations egresses) = + defMessage & PR.invocationResult + .~ ( defMessage + & PR.stateMutations .~ toList stateMutations + & PR.outgoingMessages .~ toList invocations + & PR.delayedInvocations .~ toList delayedInvocations + & PR.outgoingEgresses .~ toList egresses + ) + where + stateMutations :: [PR.FromFunction'PersistedValueMutation] + stateMutations = + [ defMessage + & PR.mutationType .~ PR.FromFunction'PersistedValueMutation'MODIFY + & PR.stateName .~ "flink_state" + & PR.stateValue .~ state + | mutated + ] + +type FlinkApi = + "statefun" :> ReqBody '[Proto] ToFunction :> Post '[Proto] FromFunction + +flinkApi :: Proxy FlinkApi +flinkApi = Proxy + +createApp :: FunctionTable -> Application +createApp funcs = serve flinkApi (flinkServer funcs) + +flinkServer :: FunctionTable -> Server FlinkApi +flinkServer functions toFunction = do + batch <- getBatch toFunction + ((initialCtx, function), (namespace, type', id')) <- findFunc (batch ^. PR.target) + result <- liftIO $ function initialCtx (Env namespace type' id') batch + finalState <- liftEither $ mapLeft flinkErrToServant result + return $ createFlinkResp finalState + where + getBatch input = maybe (throwError $ flinkErrToServant MissingInvocationBatch) return (input ^? PR.maybe'request . _Just . PR._ToFunction'Invocation') + findFunc addr = do + res <- maybe (throwError $ flinkErrToServant $ NoSuchFunction (namespace, type')) return (Map.lookup (namespace, type') functions) + return (res, address) + where + address@(namespace, type', _) = (addr ^. PR.namespace, addr ^. PR.type', addr ^. PR.id) + +flinkErrToServant :: FlinkError -> ServerError +flinkErrToServant err = case err of + MissingInvocationBatch -> err400 {errBody = "Invocation batch missing"} + ProtoUnpackError unpackErr -> err400 {errBody = "Failed to unpack protobuf Any " <> BSL.pack (show unpackErr)} + ProtoDeserializeError protoErr -> err400 {errBody = "Could not deserialize protobuf " <> BSL.pack protoErr} + StateDecodeError decodeErr -> err400 {errBody = "Invalid JSON " <> BSL.pack decodeErr} + NoSuchFunction (namespace, type') -> err400 {errBody = "No such function " <> T.encodeUtf8 (fromStrict namespace) <> T.encodeUtf8 (fromStrict type')} + +-- | Takes a `topic`, `key`, and protobuf `value` to construct 'KafkaProducerRecord's for egress +kafkaRecord :: (Message v) => Text -> Text -> v -> Kafka.KafkaProducerRecord +kafkaRecord topic k v = + defMessage + & Kafka.topic .~ topic + & Kafka.key .~ k + & Kafka.valueBytes .~ encodeMessage v