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35 #ifndef GMXAPI_CONTEXT_IMPL_H
36 #define GMXAPI_CONTEXT_IMPL_H
38 * \brief Declare gmxapi::ContextImpl
40 * \author M. Eric Irrgang <ericirrgang@gmail.com>
47 #include "gromacs/mdrun/legacymdrunoptions.h"
48 #include "gromacs/mdtypes/mdrunoptions.h"
50 #include "gmxapi/context.h"
51 #include "gmxapi/session.h"
57 * \brief Provide RAII management of communications resource state.
59 * To acquire an MpiContextManager is to have assurance that any external MPI
60 * environment is ready to use. When the MpiContextManager is released or
61 * goes out of scope, the destructor finalizes the resources.
63 * Note that thread-MPI chooses the number of ranks and constructs its
64 * MPI communicator internally, so does not and is unlikely to ever
67 * \todo There is no resource for logging or reporting errors during initialization
71 class MpiContextManager
79 * \brief Exclusive ownership of a scoped context means copying is impossible.
83 MpiContextManager(const MpiContextManager&) = delete;
84 MpiContextManager& operator=(const MpiContextManager&) = delete;
88 * \brief Move semantics are non-trivial.
92 MpiContextManager(MpiContextManager&&) noexcept = delete;
93 MpiContextManager& operator=(MpiContextManager&&) noexcept = delete;
98 * \brief Context implementation.
100 * Execution contexts have a uniform interface specified by the API. Implementations for
101 * particular execution environments can specialize / derive from this base.
103 * \todo Separate interface and implementation.
105 * \warning Definition and semantics depend on configure-time details. For example,
106 * MPI-enabled libraries always hold a valid MPI communicator via MpiContextManager,
107 * whereas tMPI and non-MPI builds hold a meaningless MpiContextManager.
109 * \todo Provide functions or traits for introspection.
113 class ContextImpl final : public std::enable_shared_from_this<ContextImpl>
119 * \brief Factory function
121 * Since this class provides `shared_from_this`, we need to make sure
122 * that it never exists without a shared_ptr owning it.
124 * If we can confirm `shared_from_this` is no longer necessary, implementation may change.
125 * \todo: Use registration/deregistration of launched Sessions to log warnings on shutdown
126 * instead of letting Session keep ContextImpl alive.
128 * \return ownership of a new object
130 static std::shared_ptr<ContextImpl> create();
133 * \brief Copy disallowed because Session state would become ambiguous.
135 * The API implementation needs to unambiguously determine
136 * which Sessions and Contexts are associated with each other.
139 ContextImpl(const ContextImpl&) = delete;
140 ContextImpl& operator=(const ContextImpl&) = delete;
144 * \brief Objects are not trivial to move.
146 * \todo Implement move semantics. Requires a moveable const MpiContextManager and
147 * LegacyMdrunOptions members.
151 ContextImpl(ContextImpl&&) = delete;
152 ContextImpl& operator=(ContextImpl&&) = delete;
156 * \brief Translate the workflow to the execution context and launch.
158 * \param work workflow graph
159 * \return ownership of a new session
161 * \todo This probably makes more sense as a free function, but we need to determine access policies.
163 * Session is returned with shared_ptr ownership so that Context
164 * can hold a weak_ptr and because Session Resources handles
165 * are still evolving.
166 * \todo Hide lifetime management and ownership from handle object.
167 * We can achieve the necessary aspects of this shared_ptr at a lower level of implementation.
168 * Note also that returned value policies can be implemented in higher level wrappers to ensure
169 * correct object lifetime scope. (See pybind, for instance.)
171 std::shared_ptr<Session> launch(const Workflow& work);
174 * \brief Retain the ability to find a launched session while it exists.
176 * The client owns the Session launched by a Context, but it is helpful
177 * for the Context to know if it has an active Session associated with it.
179 * \todo Use registration/deregistration protocol instead.
180 * Requires logging facility.
182 std::weak_ptr<Session> session_;
185 * \brief mdrun command line arguments.
187 * Store arguments provided by the client and pass them when launching
188 * a simulation runner. This allows client code to access the same
189 * options as are available to mdrun on the command line while the API
195 * \brief Legacy option-handling and set up for mdrun.
197 * This object should not exist, but is necessary now to introduce
198 * the API in a way that means CLI and API work similarly and do not
199 * duplicate definitions e.g. of command-line options.
201 gmx::LegacyMdrunOptions options_;
204 * \brief Scoped MPI management.
206 * Part of the ContextImpl invariant establishes a point where MPI initialization status is
209 * To ensure the MpiContextManager is initialized only once, we use a const member that must
210 * be initialized at construction.
212 const MpiContextManager mpi_;
216 * \brief Basic constructor.
218 * Don't use this. Use create() to get a shared pointer right away.
219 * Otherwise, shared_from_this() is potentially dangerous.
221 explicit ContextImpl() noexcept(std::is_nothrow_constructible_v<gmx::LegacyMdrunOptions>);
228 using commType = MPI_Comm;
229 MPI_Comm communicator{ MPI_COMM_NULL };
232 } // end namespace gmxapi
233 #endif // GMXAPI_CONTEXT_IMPL_H