Chris@63: // Copyright (c) 2013-2014 Sandstorm Development Group, Inc. and contributors Chris@63: // Licensed under the MIT License: Chris@63: // Chris@63: // Permission is hereby granted, free of charge, to any person obtaining a copy Chris@63: // of this software and associated documentation files (the "Software"), to deal Chris@63: // in the Software without restriction, including without limitation the rights Chris@63: // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell Chris@63: // copies of the Software, and to permit persons to whom the Software is Chris@63: // furnished to do so, subject to the following conditions: Chris@63: // Chris@63: // The above copyright notice and this permission notice shall be included in Chris@63: // all copies or substantial portions of the Software. Chris@63: // Chris@63: // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR Chris@63: // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, Chris@63: // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE Chris@63: // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER Chris@63: // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, Chris@63: // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN Chris@63: // THE SOFTWARE. Chris@63: Chris@63: #ifndef CAPNP_CAPABILITY_H_ Chris@63: #define CAPNP_CAPABILITY_H_ Chris@63: Chris@63: #if defined(__GNUC__) && !defined(CAPNP_HEADER_WARNINGS) Chris@63: #pragma GCC system_header Chris@63: #endif Chris@63: Chris@63: #if CAPNP_LITE Chris@63: #error "RPC APIs, including this header, are not available in lite mode." Chris@63: #endif Chris@63: Chris@63: #include Chris@63: #include Chris@63: #include "raw-schema.h" Chris@63: #include "any.h" Chris@63: #include "pointer-helpers.h" Chris@63: Chris@63: namespace capnp { Chris@63: Chris@63: template Chris@63: class Response; Chris@63: Chris@63: template Chris@63: class RemotePromise: public kj::Promise>, public T::Pipeline { Chris@63: // A Promise which supports pipelined calls. T is typically a struct type. T must declare Chris@63: // an inner "mix-in" type "Pipeline" which implements pipelining; RemotePromise simply Chris@63: // multiply-inherits that type along with Promise>. T::Pipeline must be movable, Chris@63: // but does not need to be copyable (i.e. just like Promise). Chris@63: // Chris@63: // The promise is for an owned pointer so that the RPC system can allocate the MessageReader Chris@63: // itself. Chris@63: Chris@63: public: Chris@63: inline RemotePromise(kj::Promise>&& promise, typename T::Pipeline&& pipeline) Chris@63: : kj::Promise>(kj::mv(promise)), Chris@63: T::Pipeline(kj::mv(pipeline)) {} Chris@63: inline RemotePromise(decltype(nullptr)) Chris@63: : kj::Promise>(nullptr), Chris@63: T::Pipeline(nullptr) {} Chris@63: KJ_DISALLOW_COPY(RemotePromise); Chris@63: RemotePromise(RemotePromise&& other) = default; Chris@63: RemotePromise& operator=(RemotePromise&& other) = default; Chris@63: }; Chris@63: Chris@63: class LocalClient; Chris@63: namespace _ { // private Chris@63: extern const RawSchema NULL_INTERFACE_SCHEMA; // defined in schema.c++ Chris@63: class CapabilityServerSetBase; Chris@63: } // namespace _ (private) Chris@63: Chris@63: struct Capability { Chris@63: // A capability without type-safe methods. Typed capability clients wrap `Client` and typed Chris@63: // capability servers subclass `Server` to dispatch to the regular, typed methods. Chris@63: Chris@63: class Client; Chris@63: class Server; Chris@63: Chris@63: struct _capnpPrivate { Chris@63: struct IsInterface; Chris@63: static constexpr uint64_t typeId = 0x3; Chris@63: static constexpr Kind kind = Kind::INTERFACE; Chris@63: static constexpr _::RawSchema const* schema = &_::NULL_INTERFACE_SCHEMA; Chris@63: Chris@63: static const _::RawBrandedSchema* brand() { Chris@63: return &_::NULL_INTERFACE_SCHEMA.defaultBrand; Chris@63: } Chris@63: }; Chris@63: }; Chris@63: Chris@63: // ======================================================================================= Chris@63: // Capability clients Chris@63: Chris@63: class RequestHook; Chris@63: class ResponseHook; Chris@63: class PipelineHook; Chris@63: class ClientHook; Chris@63: Chris@63: template Chris@63: class Request: public Params::Builder { Chris@63: // A call that hasn't been sent yet. This class extends a Builder for the call's "Params" Chris@63: // structure with a method send() that actually sends it. Chris@63: // Chris@63: // Given a Cap'n Proto method `foo(a :A, b :B): C`, the generated client interface will have Chris@63: // a method `Request fooRequest()` (as well as a convenience method Chris@63: // `RemotePromise foo(A::Reader a, B::Reader b)`). Chris@63: Chris@63: public: Chris@63: inline Request(typename Params::Builder builder, kj::Own&& hook) Chris@63: : Params::Builder(builder), hook(kj::mv(hook)) {} Chris@63: inline Request(decltype(nullptr)): Params::Builder(nullptr) {} Chris@63: Chris@63: RemotePromise send() KJ_WARN_UNUSED_RESULT; Chris@63: // Send the call and return a promise for the results. Chris@63: Chris@63: private: Chris@63: kj::Own hook; Chris@63: Chris@63: friend class Capability::Client; Chris@63: friend struct DynamicCapability; Chris@63: template Chris@63: friend class CallContext; Chris@63: friend class RequestHook; Chris@63: }; Chris@63: Chris@63: template Chris@63: class Response: public Results::Reader { Chris@63: // A completed call. This class extends a Reader for the call's answer structure. The Response Chris@63: // is move-only -- once it goes out-of-scope, the underlying message will be freed. Chris@63: Chris@63: public: Chris@63: inline Response(typename Results::Reader reader, kj::Own&& hook) Chris@63: : Results::Reader(reader), hook(kj::mv(hook)) {} Chris@63: Chris@63: private: Chris@63: kj::Own hook; Chris@63: Chris@63: template Chris@63: friend class Request; Chris@63: friend class ResponseHook; Chris@63: }; Chris@63: Chris@63: class Capability::Client { Chris@63: // Base type for capability clients. Chris@63: Chris@63: public: Chris@63: typedef Capability Reads; Chris@63: typedef Capability Calls; Chris@63: Chris@63: Client(decltype(nullptr)); Chris@63: // If you need to declare a Client before you have anything to assign to it (perhaps because Chris@63: // the assignment is going to occur in an if/else scope), you can start by initializing it to Chris@63: // `nullptr`. The resulting client is not meant to be called and throws exceptions from all Chris@63: // methods. Chris@63: Chris@63: template ()>> Chris@63: Client(kj::Own&& server); Chris@63: // Make a client capability that wraps the given server capability. The server's methods will Chris@63: // only be executed in the given EventLoop, regardless of what thread calls the client's methods. Chris@63: Chris@63: template ()>> Chris@63: Client(kj::Promise&& promise); Chris@63: // Make a client from a promise for a future client. The resulting client queues calls until the Chris@63: // promise resolves. Chris@63: Chris@63: Client(kj::Exception&& exception); Chris@63: // Make a broken client that throws the given exception from all calls. Chris@63: Chris@63: Client(Client& other); Chris@63: Client& operator=(Client& other); Chris@63: // Copies by reference counting. Warning: This refcounting is not thread-safe. All copies of Chris@63: // the client must remain in one thread. Chris@63: Chris@63: Client(Client&&) = default; Chris@63: Client& operator=(Client&&) = default; Chris@63: // Move constructor avoids reference counting. Chris@63: Chris@63: explicit Client(kj::Own&& hook); Chris@63: // For use by the RPC implementation: Wrap a ClientHook. Chris@63: Chris@63: template Chris@63: typename T::Client castAs(); Chris@63: // Reinterpret the capability as implementing the given interface. Note that no error will occur Chris@63: // here if the capability does not actually implement this interface, but later method calls will Chris@63: // fail. It's up to the application to decide how indicate that additional interfaces are Chris@63: // supported. Chris@63: // Chris@63: // TODO(perf): GCC 4.8 / Clang 3.3: rvalue-qualified version for better performance. Chris@63: Chris@63: template Chris@63: typename T::Client castAs(InterfaceSchema schema); Chris@63: // Dynamic version. `T` must be `DynamicCapability`, and you must `#include `. Chris@63: Chris@63: kj::Promise whenResolved(); Chris@63: // If the capability is actually only a promise, the returned promise resolves once the Chris@63: // capability itself has resolved to its final destination (or propagates the exception if Chris@63: // the capability promise is rejected). This is mainly useful for error-checking in the case Chris@63: // where no calls are being made. There is no reason to wait for this before making calls; if Chris@63: // the capability does not resolve, the call results will propagate the error. Chris@63: Chris@63: Request typelessRequest( Chris@63: uint64_t interfaceId, uint16_t methodId, Chris@63: kj::Maybe sizeHint); Chris@63: // Make a request without knowing the types of the params or results. You specify the type ID Chris@63: // and method number manually. Chris@63: Chris@63: // TODO(someday): method(s) for Join Chris@63: Chris@63: protected: Chris@63: Client() = default; Chris@63: Chris@63: template Chris@63: Request newCall(uint64_t interfaceId, uint16_t methodId, Chris@63: kj::Maybe sizeHint); Chris@63: Chris@63: private: Chris@63: kj::Own hook; Chris@63: Chris@63: static kj::Own makeLocalClient(kj::Own&& server); Chris@63: Chris@63: template Chris@63: friend struct _::PointerHelpers; Chris@63: friend struct DynamicCapability; Chris@63: friend class Orphanage; Chris@63: friend struct DynamicStruct; Chris@63: friend struct DynamicList; Chris@63: template Chris@63: friend struct List; Chris@63: friend class _::CapabilityServerSetBase; Chris@63: friend class ClientHook; Chris@63: }; Chris@63: Chris@63: // ======================================================================================= Chris@63: // Capability servers Chris@63: Chris@63: class CallContextHook; Chris@63: Chris@63: template Chris@63: class CallContext: public kj::DisallowConstCopy { Chris@63: // Wrapper around CallContextHook with a specific return type. Chris@63: // Chris@63: // Methods of this class may only be called from within the server's event loop, not from other Chris@63: // threads. Chris@63: // Chris@63: // The CallContext becomes invalid as soon as the call reports completion. Chris@63: Chris@63: public: Chris@63: explicit CallContext(CallContextHook& hook); Chris@63: Chris@63: typename Params::Reader getParams(); Chris@63: // Get the params payload. Chris@63: Chris@63: void releaseParams(); Chris@63: // Release the params payload. getParams() will throw an exception after this is called. Chris@63: // Releasing the params may allow the RPC system to free up buffer space to handle other Chris@63: // requests. Long-running asynchronous methods should try to call this as early as is Chris@63: // convenient. Chris@63: Chris@63: typename Results::Builder getResults(kj::Maybe sizeHint = nullptr); Chris@63: typename Results::Builder initResults(kj::Maybe sizeHint = nullptr); Chris@63: void setResults(typename Results::Reader value); Chris@63: void adoptResults(Orphan&& value); Chris@63: Orphanage getResultsOrphanage(kj::Maybe sizeHint = nullptr); Chris@63: // Manipulate the results payload. The "Return" message (part of the RPC protocol) will Chris@63: // typically be allocated the first time one of these is called. Some RPC systems may Chris@63: // allocate these messages in a limited space (such as a shared memory segment), therefore the Chris@63: // application should delay calling these as long as is convenient to do so (but don't delay Chris@63: // if doing so would require extra copies later). Chris@63: // Chris@63: // `sizeHint` indicates a guess at the message size. This will usually be used to decide how Chris@63: // much space to allocate for the first message segment (don't worry: only space that is actually Chris@63: // used will be sent on the wire). If omitted, the system decides. The message root pointer Chris@63: // should not be included in the size. So, if you are simply going to copy some existing message Chris@63: // directly into the results, just call `.totalSize()` and pass that in. Chris@63: Chris@63: template Chris@63: kj::Promise tailCall(Request&& tailRequest); Chris@63: // Resolve the call by making a tail call. `tailRequest` is a request that has been filled in Chris@63: // but not yet sent. The context will send the call, then fill in the results with the result Chris@63: // of the call. If tailCall() is used, {get,init,set,adopt}Results (above) *must not* be called. Chris@63: // Chris@63: // The RPC implementation may be able to optimize a tail call to another machine such that the Chris@63: // results never actually pass through this machine. Even if no such optimization is possible, Chris@63: // `tailCall()` may allow pipelined calls to be forwarded optimistically to the new call site. Chris@63: // Chris@63: // In general, this should be the last thing a method implementation calls, and the promise Chris@63: // returned from `tailCall()` should then be returned by the method implementation. Chris@63: Chris@63: void allowCancellation(); Chris@63: // Indicate that it is OK for the RPC system to discard its Promise for this call's result if Chris@63: // the caller cancels the call, thereby transitively canceling any asynchronous operations the Chris@63: // call implementation was performing. This is not done by default because it could represent a Chris@63: // security risk: applications must be carefully written to ensure that they do not end up in Chris@63: // a bad state if an operation is canceled at an arbitrary point. However, for long-running Chris@63: // method calls that hold significant resources, prompt cancellation is often useful. Chris@63: // Chris@63: // Keep in mind that asynchronous cancellation cannot occur while the method is synchronously Chris@63: // executing on a local thread. The method must perform an asynchronous operation or call Chris@63: // `EventLoop::current().evalLater()` to yield control. Chris@63: // Chris@63: // Note: You might think that we should offer `onCancel()` and/or `isCanceled()` methods that Chris@63: // provide notification when the caller cancels the request without forcefully killing off the Chris@63: // promise chain. Unfortunately, this composes poorly with promise forking: the canceled Chris@63: // path may be just one branch of a fork of the result promise. The other branches still want Chris@63: // the call to continue. Promise forking is used within the Cap'n Proto implementation -- in Chris@63: // particular each pipelined call forks the result promise. So, if a caller made a pipelined Chris@63: // call and then dropped the original object, the call should not be canceled, but it would be Chris@63: // excessively complicated for the framework to avoid notififying of cancellation as long as Chris@63: // pipelined calls still exist. Chris@63: Chris@63: private: Chris@63: CallContextHook* hook; Chris@63: Chris@63: friend class Capability::Server; Chris@63: friend struct DynamicCapability; Chris@63: }; Chris@63: Chris@63: class Capability::Server { Chris@63: // Objects implementing a Cap'n Proto interface must subclass this. Typically, such objects Chris@63: // will instead subclass a typed Server interface which will take care of implementing Chris@63: // dispatchCall(). Chris@63: Chris@63: public: Chris@63: typedef Capability Serves; Chris@63: Chris@63: virtual kj::Promise dispatchCall(uint64_t interfaceId, uint16_t methodId, Chris@63: CallContext context) = 0; Chris@63: // Call the given method. `params` is the input struct, and should be released as soon as it Chris@63: // is no longer needed. `context` may be used to allocate the output struct and deal with Chris@63: // cancellation. Chris@63: Chris@63: // TODO(someday): Method which can optionally be overridden to implement Join when the object is Chris@63: // a proxy. Chris@63: Chris@63: protected: Chris@63: inline Capability::Client thisCap(); Chris@63: // Get a capability pointing to this object, much like the `this` keyword. Chris@63: // Chris@63: // The effect of this method is undefined if: Chris@63: // - No capability client has been created pointing to this object. (This is always the case in Chris@63: // the server's constructor.) Chris@63: // - The capability client pointing at this object has been destroyed. (This is always the case Chris@63: // in the server's destructor.) Chris@63: // - Multiple capability clients have been created around the same server (possible if the server Chris@63: // is refcounted, which is not recommended since the client itself provides refcounting). Chris@63: Chris@63: template Chris@63: CallContext internalGetTypedContext( Chris@63: CallContext typeless); Chris@63: kj::Promise internalUnimplemented(const char* actualInterfaceName, Chris@63: uint64_t requestedTypeId); Chris@63: kj::Promise internalUnimplemented(const char* interfaceName, Chris@63: uint64_t typeId, uint16_t methodId); Chris@63: kj::Promise internalUnimplemented(const char* interfaceName, const char* methodName, Chris@63: uint64_t typeId, uint16_t methodId); Chris@63: Chris@63: private: Chris@63: ClientHook* thisHook = nullptr; Chris@63: friend class LocalClient; Chris@63: }; Chris@63: Chris@63: // ======================================================================================= Chris@63: Chris@63: class ReaderCapabilityTable: private _::CapTableReader { Chris@63: // Class which imbues Readers with the ability to read capabilities. Chris@63: // Chris@63: // In Cap'n Proto format, the encoding of a capability pointer is simply an integer index into Chris@63: // an external table. Since these pointers fundamentally point outside the message, a Chris@63: // MessageReader by default has no idea what they point at, and therefore reading capabilities Chris@63: // from such a reader will throw exceptions. Chris@63: // Chris@63: // In order to be able to read capabilities, you must first attach a capability table, using Chris@63: // this class. By "imbuing" a Reader, you get a new Reader which will interpret capability Chris@63: // pointers by treating them as indexes into the ReaderCapabilityTable. Chris@63: // Chris@63: // Note that when using Cap'n Proto's RPC system, this is handled automatically. Chris@63: Chris@63: public: Chris@63: explicit ReaderCapabilityTable(kj::Array>> table); Chris@63: KJ_DISALLOW_COPY(ReaderCapabilityTable); Chris@63: Chris@63: template Chris@63: T imbue(T reader); Chris@63: // Return a reader equivalent to `reader` except that when reading capability-valued fields, Chris@63: // the capabilities are looked up in this table. Chris@63: Chris@63: private: Chris@63: kj::Array>> table; Chris@63: Chris@63: kj::Maybe> extractCap(uint index) override; Chris@63: }; Chris@63: Chris@63: class BuilderCapabilityTable: private _::CapTableBuilder { Chris@63: // Class which imbues Builders with the ability to read and write capabilities. Chris@63: // Chris@63: // This is much like ReaderCapabilityTable, except for builders. The table starts out empty, Chris@63: // but capabilities can be added to it over time. Chris@63: Chris@63: public: Chris@63: BuilderCapabilityTable(); Chris@63: KJ_DISALLOW_COPY(BuilderCapabilityTable); Chris@63: Chris@63: inline kj::ArrayPtr>> getTable() { return table; } Chris@63: Chris@63: template Chris@63: T imbue(T builder); Chris@63: // Return a builder equivalent to `builder` except that when reading capability-valued fields, Chris@63: // the capabilities are looked up in this table. Chris@63: Chris@63: private: Chris@63: kj::Vector>> table; Chris@63: Chris@63: kj::Maybe> extractCap(uint index) override; Chris@63: uint injectCap(kj::Own&& cap) override; Chris@63: void dropCap(uint index) override; Chris@63: }; Chris@63: Chris@63: // ======================================================================================= Chris@63: Chris@63: namespace _ { // private Chris@63: Chris@63: class CapabilityServerSetBase { Chris@63: public: Chris@63: Capability::Client addInternal(kj::Own&& server, void* ptr); Chris@63: kj::Promise getLocalServerInternal(Capability::Client& client); Chris@63: }; Chris@63: Chris@63: } // namespace _ (private) Chris@63: Chris@63: template Chris@63: class CapabilityServerSet: private _::CapabilityServerSetBase { Chris@63: // Allows a server to recognize its own capabilities when passed back to it, and obtain the Chris@63: // underlying Server objects associated with them. Chris@63: // Chris@63: // All objects in the set must have the same interface type T. The objects may implement various Chris@63: // interfaces derived from T (and in fact T can be `capnp::Capability` to accept all objects), Chris@63: // but note that if you compile with RTTI disabled then you will not be able to down-cast through Chris@63: // virtual inheritance, and all inheritance between server interfaces is virtual. So, with RTTI Chris@63: // disabled, you will likely need to set T to be the most-derived Cap'n Proto interface type, Chris@63: // and you server class will need to be directly derived from that, so that you can use Chris@63: // static_cast (or kj::downcast) to cast to it after calling getLocalServer(). (If you compile Chris@63: // with RTTI, then you can freely dynamic_cast and ignore this issue!) Chris@63: Chris@63: public: Chris@63: CapabilityServerSet() = default; Chris@63: KJ_DISALLOW_COPY(CapabilityServerSet); Chris@63: Chris@63: typename T::Client add(kj::Own&& server); Chris@63: // Create a new capability Client for the given Server and also add this server to the set. Chris@63: Chris@63: kj::Promise> getLocalServer(typename T::Client& client); Chris@63: // Given a Client pointing to a server previously passed to add(), return the corresponding Chris@63: // Server. This returns a promise because if the input client is itself a promise, this must Chris@63: // wait for it to resolve. Keep in mind that the server will be deleted when all clients are Chris@63: // gone, so the caller should make sure to keep the client alive (hence why this method only Chris@63: // accepts an lvalue input). Chris@63: }; Chris@63: Chris@63: // ======================================================================================= Chris@63: // Hook interfaces which must be implemented by the RPC system. Applications never call these Chris@63: // directly; the RPC system implements them and the types defined earlier in this file wrap them. Chris@63: Chris@63: class RequestHook { Chris@63: // Hook interface implemented by RPC system representing a request being built. Chris@63: Chris@63: public: Chris@63: virtual RemotePromise send() = 0; Chris@63: // Send the call and return a promise for the result. Chris@63: Chris@63: virtual const void* getBrand() = 0; Chris@63: // Returns a void* that identifies who made this request. This can be used by an RPC adapter to Chris@63: // discover when tail call is going to be sent over its own connection and therefore can be Chris@63: // optimized into a remote tail call. Chris@63: Chris@63: template Chris@63: inline static kj::Own from(Request&& request) { Chris@63: return kj::mv(request.hook); Chris@63: } Chris@63: }; Chris@63: Chris@63: class ResponseHook { Chris@63: // Hook interface implemented by RPC system representing a response. Chris@63: // Chris@63: // At present this class has no methods. It exists only for garbage collection -- when the Chris@63: // ResponseHook is destroyed, the results can be freed. Chris@63: Chris@63: public: Chris@63: virtual ~ResponseHook() noexcept(false); Chris@63: // Just here to make sure the type is dynamic. Chris@63: Chris@63: template Chris@63: inline static kj::Own from(Response&& response) { Chris@63: return kj::mv(response.hook); Chris@63: } Chris@63: }; Chris@63: Chris@63: // class PipelineHook is declared in any.h because it is needed there. Chris@63: Chris@63: class ClientHook { Chris@63: public: Chris@63: ClientHook(); Chris@63: Chris@63: virtual Request newCall( Chris@63: uint64_t interfaceId, uint16_t methodId, kj::Maybe sizeHint) = 0; Chris@63: // Start a new call, allowing the client to allocate request/response objects as it sees fit. Chris@63: // This version is used when calls are made from application code in the local process. Chris@63: Chris@63: struct VoidPromiseAndPipeline { Chris@63: kj::Promise promise; Chris@63: kj::Own pipeline; Chris@63: }; Chris@63: Chris@63: virtual VoidPromiseAndPipeline call(uint64_t interfaceId, uint16_t methodId, Chris@63: kj::Own&& context) = 0; Chris@63: // Call the object, but the caller controls allocation of the request/response objects. If the Chris@63: // callee insists on allocating these objects itself, it must make a copy. This version is used Chris@63: // when calls come in over the network via an RPC system. Note that even if the returned Chris@63: // `Promise` is discarded, the call may continue executing if any pipelined calls are Chris@63: // waiting for it. Chris@63: // Chris@63: // Since the caller of this method chooses the CallContext implementation, it is the caller's Chris@63: // responsibility to ensure that the returned promise is not canceled unless allowed via Chris@63: // the context's `allowCancellation()`. Chris@63: // Chris@63: // The call must not begin synchronously; the callee must arrange for the call to begin in a Chris@63: // later turn of the event loop. Otherwise, application code may call back and affect the Chris@63: // callee's state in an unexpected way. Chris@63: Chris@63: virtual kj::Maybe getResolved() = 0; Chris@63: // If this ClientHook is a promise that has already resolved, returns the inner, resolved version Chris@63: // of the capability. The caller may permanently replace this client with the resolved one if Chris@63: // desired. Returns null if the client isn't a promise or hasn't resolved yet -- use Chris@63: // `whenMoreResolved()` to distinguish between them. Chris@63: Chris@63: virtual kj::Maybe>> whenMoreResolved() = 0; Chris@63: // If this client is a settled reference (not a promise), return nullptr. Otherwise, return a Chris@63: // promise that eventually resolves to a new client that is closer to being the final, settled Chris@63: // client (i.e. the value eventually returned by `getResolved()`). Calling this repeatedly Chris@63: // should eventually produce a settled client. Chris@63: Chris@63: kj::Promise whenResolved(); Chris@63: // Repeatedly calls whenMoreResolved() until it returns nullptr. Chris@63: Chris@63: virtual kj::Own addRef() = 0; Chris@63: // Return a new reference to the same capability. Chris@63: Chris@63: virtual const void* getBrand() = 0; Chris@63: // Returns a void* that identifies who made this client. This can be used by an RPC adapter to Chris@63: // discover when a capability it needs to marshal is one that it created in the first place, and Chris@63: // therefore it can transfer the capability without proxying. Chris@63: Chris@63: static const uint NULL_CAPABILITY_BRAND; Chris@63: // Value is irrelevant; used for pointer. Chris@63: Chris@63: inline bool isNull() { return getBrand() == &NULL_CAPABILITY_BRAND; } Chris@63: // Returns true if the capability was created as a result of assigning a Client to null or by Chris@63: // reading a null pointer out of a Cap'n Proto message. Chris@63: Chris@63: virtual void* getLocalServer(_::CapabilityServerSetBase& capServerSet); Chris@63: // If this is a local capability created through `capServerSet`, return the underlying Server. Chris@63: // Otherwise, return nullptr. Default implementation (which everyone except LocalClient should Chris@63: // use) always returns nullptr. Chris@63: Chris@63: static kj::Own from(Capability::Client client) { return kj::mv(client.hook); } Chris@63: }; Chris@63: Chris@63: class CallContextHook { Chris@63: // Hook interface implemented by RPC system to manage a call on the server side. See Chris@63: // CallContext. Chris@63: Chris@63: public: Chris@63: virtual AnyPointer::Reader getParams() = 0; Chris@63: virtual void releaseParams() = 0; Chris@63: virtual AnyPointer::Builder getResults(kj::Maybe sizeHint) = 0; Chris@63: virtual kj::Promise tailCall(kj::Own&& request) = 0; Chris@63: virtual void allowCancellation() = 0; Chris@63: Chris@63: virtual kj::Promise onTailCall() = 0; Chris@63: // If `tailCall()` is called, resolves to the PipelineHook from the tail call. An Chris@63: // implementation of `ClientHook::call()` is allowed to call this at most once. Chris@63: Chris@63: virtual ClientHook::VoidPromiseAndPipeline directTailCall(kj::Own&& request) = 0; Chris@63: // Call this when you would otherwise call onTailCall() immediately followed by tailCall(). Chris@63: // Implementations of tailCall() should typically call directTailCall() and then fulfill the Chris@63: // promise fulfiller for onTailCall() with the returned pipeline. Chris@63: Chris@63: virtual kj::Own addRef() = 0; Chris@63: }; Chris@63: Chris@63: kj::Own newLocalPromiseClient(kj::Promise>&& promise); Chris@63: // Returns a ClientHook that queues up calls until `promise` resolves, then forwards them to Chris@63: // the new client. This hook's `getResolved()` and `whenMoreResolved()` methods will reflect the Chris@63: // redirection to the eventual replacement client. Chris@63: Chris@63: kj::Own newLocalPromisePipeline(kj::Promise>&& promise); Chris@63: // Returns a PipelineHook that queues up calls until `promise` resolves, then forwards them to Chris@63: // the new pipeline. Chris@63: Chris@63: kj::Own newBrokenCap(kj::StringPtr reason); Chris@63: kj::Own newBrokenCap(kj::Exception&& reason); Chris@63: // Helper function that creates a capability which simply throws exceptions when called. Chris@63: Chris@63: kj::Own newBrokenPipeline(kj::Exception&& reason); Chris@63: // Helper function that creates a pipeline which simply throws exceptions when called. Chris@63: Chris@63: Request newBrokenRequest( Chris@63: kj::Exception&& reason, kj::Maybe sizeHint); Chris@63: // Helper function that creates a Request object that simply throws exceptions when sent. Chris@63: Chris@63: // ======================================================================================= Chris@63: // Extend PointerHelpers for interfaces Chris@63: Chris@63: namespace _ { // private Chris@63: Chris@63: template Chris@63: struct PointerHelpers { Chris@63: static inline typename T::Client get(PointerReader reader) { Chris@63: return typename T::Client(reader.getCapability()); Chris@63: } Chris@63: static inline typename T::Client get(PointerBuilder builder) { Chris@63: return typename T::Client(builder.getCapability()); Chris@63: } Chris@63: static inline void set(PointerBuilder builder, typename T::Client&& value) { Chris@63: builder.setCapability(kj::mv(value.Capability::Client::hook)); Chris@63: } Chris@63: static inline void set(PointerBuilder builder, typename T::Client& value) { Chris@63: builder.setCapability(value.Capability::Client::hook->addRef()); Chris@63: } Chris@63: static inline void adopt(PointerBuilder builder, Orphan&& value) { Chris@63: builder.adopt(kj::mv(value.builder)); Chris@63: } Chris@63: static inline Orphan disown(PointerBuilder builder) { Chris@63: return Orphan(builder.disown()); Chris@63: } Chris@63: }; Chris@63: Chris@63: } // namespace _ (private) Chris@63: Chris@63: // ======================================================================================= Chris@63: // Extend List for interfaces Chris@63: Chris@63: template Chris@63: struct List { Chris@63: List() = delete; Chris@63: Chris@63: class Reader { Chris@63: public: Chris@63: typedef List Reads; Chris@63: Chris@63: Reader() = default; Chris@63: inline explicit Reader(_::ListReader reader): reader(reader) {} Chris@63: Chris@63: inline uint size() const { return unbound(reader.size() / ELEMENTS); } Chris@63: inline typename T::Client operator[](uint index) const { Chris@63: KJ_IREQUIRE(index < size()); Chris@63: return typename T::Client(reader.getPointerElement( Chris@63: bounded(index) * ELEMENTS).getCapability()); Chris@63: } Chris@63: Chris@63: typedef _::IndexingIterator Iterator; Chris@63: inline Iterator begin() const { return Iterator(this, 0); } Chris@63: inline Iterator end() const { return Iterator(this, size()); } Chris@63: Chris@63: private: Chris@63: _::ListReader reader; Chris@63: template Chris@63: friend struct _::PointerHelpers; Chris@63: template Chris@63: friend struct List; Chris@63: friend class Orphanage; Chris@63: template Chris@63: friend struct ToDynamic_; Chris@63: }; Chris@63: Chris@63: class Builder { Chris@63: public: Chris@63: typedef List Builds; Chris@63: Chris@63: Builder() = delete; Chris@63: inline Builder(decltype(nullptr)) {} Chris@63: inline explicit Builder(_::ListBuilder builder): builder(builder) {} Chris@63: Chris@63: inline operator Reader() const { return Reader(builder.asReader()); } Chris@63: inline Reader asReader() const { return Reader(builder.asReader()); } Chris@63: Chris@63: inline uint size() const { return unbound(builder.size() / ELEMENTS); } Chris@63: inline typename T::Client operator[](uint index) { Chris@63: KJ_IREQUIRE(index < size()); Chris@63: return typename T::Client(builder.getPointerElement( Chris@63: bounded(index) * ELEMENTS).getCapability()); Chris@63: } Chris@63: inline void set(uint index, typename T::Client value) { Chris@63: KJ_IREQUIRE(index < size()); Chris@63: builder.getPointerElement(bounded(index) * ELEMENTS).setCapability(kj::mv(value.hook)); Chris@63: } Chris@63: inline void adopt(uint index, Orphan&& value) { Chris@63: KJ_IREQUIRE(index < size()); Chris@63: builder.getPointerElement(bounded(index) * ELEMENTS).adopt(kj::mv(value)); Chris@63: } Chris@63: inline Orphan disown(uint index) { Chris@63: KJ_IREQUIRE(index < size()); Chris@63: return Orphan(builder.getPointerElement(bounded(index) * ELEMENTS).disown()); Chris@63: } Chris@63: Chris@63: typedef _::IndexingIterator Iterator; Chris@63: inline Iterator begin() { return Iterator(this, 0); } Chris@63: inline Iterator end() { return Iterator(this, size()); } Chris@63: Chris@63: private: Chris@63: _::ListBuilder builder; Chris@63: friend class Orphanage; Chris@63: template Chris@63: friend struct ToDynamic_; Chris@63: }; Chris@63: Chris@63: private: Chris@63: inline static _::ListBuilder initPointer(_::PointerBuilder builder, uint size) { Chris@63: return builder.initList(ElementSize::POINTER, bounded(size) * ELEMENTS); Chris@63: } Chris@63: inline static _::ListBuilder getFromPointer(_::PointerBuilder builder, const word* defaultValue) { Chris@63: return builder.getList(ElementSize::POINTER, defaultValue); Chris@63: } Chris@63: inline static _::ListReader getFromPointer( Chris@63: const _::PointerReader& reader, const word* defaultValue) { Chris@63: return reader.getList(ElementSize::POINTER, defaultValue); Chris@63: } Chris@63: Chris@63: template Chris@63: friend struct List; Chris@63: template Chris@63: friend struct _::PointerHelpers; Chris@63: }; Chris@63: Chris@63: // ======================================================================================= Chris@63: // Inline implementation details Chris@63: Chris@63: template Chris@63: RemotePromise Request::send() { Chris@63: auto typelessPromise = hook->send(); Chris@63: hook = nullptr; // prevent reuse Chris@63: Chris@63: // Convert the Promise to return the correct response type. Chris@63: // Explicitly upcast to kj::Promise to make clear that calling .then() doesn't invalidate the Chris@63: // Pipeline part of the RemotePromise. Chris@63: auto typedPromise = kj::implicitCast>&>(typelessPromise) Chris@63: .then([](Response&& response) -> Response { Chris@63: return Response(response.getAs(), kj::mv(response.hook)); Chris@63: }); Chris@63: Chris@63: // Wrap the typeless pipeline in a typed wrapper. Chris@63: typename Results::Pipeline typedPipeline( Chris@63: kj::mv(kj::implicitCast(typelessPromise))); Chris@63: Chris@63: return RemotePromise(kj::mv(typedPromise), kj::mv(typedPipeline)); Chris@63: } Chris@63: Chris@63: inline Capability::Client::Client(kj::Own&& hook): hook(kj::mv(hook)) {} Chris@63: template Chris@63: inline Capability::Client::Client(kj::Own&& server) Chris@63: : hook(makeLocalClient(kj::mv(server))) {} Chris@63: template Chris@63: inline Capability::Client::Client(kj::Promise&& promise) Chris@63: : hook(newLocalPromiseClient(promise.then([](T&& t) { return kj::mv(t.hook); }))) {} Chris@63: inline Capability::Client::Client(Client& other): hook(other.hook->addRef()) {} Chris@63: inline Capability::Client& Capability::Client::operator=(Client& other) { Chris@63: hook = other.hook->addRef(); Chris@63: return *this; Chris@63: } Chris@63: template Chris@63: inline typename T::Client Capability::Client::castAs() { Chris@63: return typename T::Client(hook->addRef()); Chris@63: } Chris@63: inline kj::Promise Capability::Client::whenResolved() { Chris@63: return hook->whenResolved(); Chris@63: } Chris@63: inline Request Capability::Client::typelessRequest( Chris@63: uint64_t interfaceId, uint16_t methodId, Chris@63: kj::Maybe sizeHint) { Chris@63: return newCall(interfaceId, methodId, sizeHint); Chris@63: } Chris@63: template Chris@63: inline Request Capability::Client::newCall( Chris@63: uint64_t interfaceId, uint16_t methodId, kj::Maybe sizeHint) { Chris@63: auto typeless = hook->newCall(interfaceId, methodId, sizeHint); Chris@63: return Request(typeless.template getAs(), kj::mv(typeless.hook)); Chris@63: } Chris@63: Chris@63: template Chris@63: inline CallContext::CallContext(CallContextHook& hook): hook(&hook) {} Chris@63: template Chris@63: inline typename Params::Reader CallContext::getParams() { Chris@63: return hook->getParams().template getAs(); Chris@63: } Chris@63: template Chris@63: inline void CallContext::releaseParams() { Chris@63: hook->releaseParams(); Chris@63: } Chris@63: template Chris@63: inline typename Results::Builder CallContext::getResults( Chris@63: kj::Maybe sizeHint) { Chris@63: // `template` keyword needed due to: http://llvm.org/bugs/show_bug.cgi?id=17401 Chris@63: return hook->getResults(sizeHint).template getAs(); Chris@63: } Chris@63: template Chris@63: inline typename Results::Builder CallContext::initResults( Chris@63: kj::Maybe sizeHint) { Chris@63: // `template` keyword needed due to: http://llvm.org/bugs/show_bug.cgi?id=17401 Chris@63: return hook->getResults(sizeHint).template initAs(); Chris@63: } Chris@63: template Chris@63: inline void CallContext::setResults(typename Results::Reader value) { Chris@63: hook->getResults(value.totalSize()).template setAs(value); Chris@63: } Chris@63: template Chris@63: inline void CallContext::adoptResults(Orphan&& value) { Chris@63: hook->getResults(nullptr).adopt(kj::mv(value)); Chris@63: } Chris@63: template Chris@63: inline Orphanage CallContext::getResultsOrphanage( Chris@63: kj::Maybe sizeHint) { Chris@63: return Orphanage::getForMessageContaining(hook->getResults(sizeHint)); Chris@63: } Chris@63: template Chris@63: template Chris@63: inline kj::Promise CallContext::tailCall( Chris@63: Request&& tailRequest) { Chris@63: return hook->tailCall(kj::mv(tailRequest.hook)); Chris@63: } Chris@63: template Chris@63: inline void CallContext::allowCancellation() { Chris@63: hook->allowCancellation(); Chris@63: } Chris@63: Chris@63: template Chris@63: CallContext Capability::Server::internalGetTypedContext( Chris@63: CallContext typeless) { Chris@63: return CallContext(*typeless.hook); Chris@63: } Chris@63: Chris@63: Capability::Client Capability::Server::thisCap() { Chris@63: return Client(thisHook->addRef()); Chris@63: } Chris@63: Chris@63: template Chris@63: T ReaderCapabilityTable::imbue(T reader) { Chris@63: return T(_::PointerHelpers>::getInternalReader(reader).imbue(this)); Chris@63: } Chris@63: Chris@63: template Chris@63: T BuilderCapabilityTable::imbue(T builder) { Chris@63: return T(_::PointerHelpers>::getInternalBuilder(kj::mv(builder)).imbue(this)); Chris@63: } Chris@63: Chris@63: template Chris@63: typename T::Client CapabilityServerSet::add(kj::Own&& server) { Chris@63: void* ptr = reinterpret_cast(server.get()); Chris@63: // Clang insists that `castAs` is a template-dependent member and therefore we need the Chris@63: // `template` keyword here, but AFAICT this is wrong: addImpl() is not a template. Chris@63: return addInternal(kj::mv(server), ptr).template castAs(); Chris@63: } Chris@63: Chris@63: template Chris@63: kj::Promise> CapabilityServerSet::getLocalServer( Chris@63: typename T::Client& client) { Chris@63: return getLocalServerInternal(client) Chris@63: .then([](void* server) -> kj::Maybe { Chris@63: if (server == nullptr) { Chris@63: return nullptr; Chris@63: } else { Chris@63: return *reinterpret_cast(server); Chris@63: } Chris@63: }); Chris@63: } Chris@63: Chris@63: template Chris@63: struct Orphanage::GetInnerReader { Chris@63: static inline kj::Own apply(typename T::Client t) { Chris@63: return ClientHook::from(kj::mv(t)); Chris@63: } Chris@63: }; Chris@63: Chris@63: } // namespace capnp Chris@63: Chris@63: #endif // CAPNP_CAPABILITY_H_