+++ /dev/null
-/* ---------------------------------------------------------------------------
- *
- * (c) The GHC Team, 2001-2006
- *
- * Capabilities
- *
- * The notion of a capability is used when operating in multi-threaded
- * environments (which the THREADED_RTS build of the RTS does), to
- * hold all the state an OS thread/task needs to run Haskell code:
- * its STG registers, a pointer to its TSO, a nursery etc. During
- * STG execution, a pointer to the capabilitity is kept in a
- * register (BaseReg).
- *
- * Only in an THREADED_RTS build will there be multiple capabilities,
- * in the non-threaded builds there is one global capability, namely
- * MainCapability.
- *
- * This header file contains the functions for working with capabilities.
- * (the main, and only, consumer of this interface is the scheduler).
- *
- * --------------------------------------------------------------------------*/
-
-#ifndef CAPABILITY_H
-#define CAPABILITY_H
-
-#include "RtsFlags.h"
-#include "Task.h"
-
-struct Capability_ {
- // State required by the STG virtual machine when running Haskell
- // code. During STG execution, the BaseReg register always points
- // to the StgRegTable of the current Capability (&cap->r).
- StgFunTable f;
- StgRegTable r;
-
- nat no; // capability number.
-
- // The Task currently holding this Capability. This task has
- // exclusive access to the contents of this Capability (apart from
- // returning_tasks_hd/returning_tasks_tl).
- // Locks required: cap->lock.
- Task *running_task;
-
- // true if this Capability is running Haskell code, used for
- // catching unsafe call-ins.
- rtsBool in_haskell;
-
- // The run queue. The Task owning this Capability has exclusive
- // access to its run queue, so can wake up threads without
- // taking a lock, and the common path through the scheduler is
- // also lock-free.
- StgTSO *run_queue_hd;
- StgTSO *run_queue_tl;
-
- // Tasks currently making safe foreign calls. Doubly-linked.
- // When returning, a task first acquires the Capability before
- // removing itself from this list, so that the GC can find all
- // the suspended TSOs easily. Hence, when migrating a Task from
- // the returning_tasks list, we must also migrate its entry from
- // this list.
- Task *suspended_ccalling_tasks;
-
- // One mutable list per generation, so we don't need to take any
- // locks when updating an old-generation thunk. These
- // mini-mut-lists are moved onto the respective gen->mut_list at
- // each GC.
- bdescr **mut_lists;
-
-#if defined(THREADED_RTS)
- // Worker Tasks waiting in the wings. Singly-linked.
- Task *spare_workers;
-
- // This lock protects running_task, returning_tasks_{hd,tl}, wakeup_queue.
- Mutex lock;
-
- // Tasks waiting to return from a foreign call, or waiting to make
- // a new call-in using this Capability (NULL if empty).
- // NB. this field needs to be modified by tasks other than the
- // running_task, so it requires cap->lock to modify. A task can
- // check whether it is NULL without taking the lock, however.
- Task *returning_tasks_hd; // Singly-linked, with head/tail
- Task *returning_tasks_tl;
-
- // A list of threads to append to this Capability's run queue at
- // the earliest opportunity. These are threads that have been
- // woken up by another Capability.
- StgTSO *wakeup_queue_hd;
- StgTSO *wakeup_queue_tl;
-#endif
-
- // Per-capability STM-related data
- StgTVarWaitQueue *free_tvar_wait_queues;
- StgTRecChunk *free_trec_chunks;
- StgTRecHeader *free_trec_headers;
- nat transaction_tokens;
-}; // typedef Capability, defined in RtsAPI.h
-
-
-#if defined(THREADED_RTS)
-#define ASSERT_TASK_ID(task) ASSERT(task->id == osThreadId())
-#else
-#define ASSERT_TASK_ID(task) /*empty*/
-#endif
-
-// These properties should be true when a Task is holding a Capability
-#define ASSERT_FULL_CAPABILITY_INVARIANTS(cap,task) \
- ASSERT(cap->running_task != NULL && cap->running_task == task); \
- ASSERT(task->cap == cap); \
- ASSERT_PARTIAL_CAPABILITY_INVARIANTS(cap,task)
-
-// Sometimes a Task holds a Capability, but the Task is not associated
-// with that Capability (ie. task->cap != cap). This happens when
-// (a) a Task holds multiple Capabilities, and (b) when the current
-// Task is bound, its thread has just blocked, and it may have been
-// moved to another Capability.
-#define ASSERT_PARTIAL_CAPABILITY_INVARIANTS(cap,task) \
- ASSERT(cap->run_queue_hd == END_TSO_QUEUE ? \
- cap->run_queue_tl == END_TSO_QUEUE : 1); \
- ASSERT(myTask() == task); \
- ASSERT_TASK_ID(task);
-
-// Converts a *StgRegTable into a *Capability.
-//
-INLINE_HEADER Capability *
-regTableToCapability (StgRegTable *reg)
-{
- return (Capability *)((void *)((unsigned char*)reg - sizeof(StgFunTable)));
-}
-
-// Initialise the available capabilities.
-//
-void initCapabilities (void);
-
-// Release a capability. This is called by a Task that is exiting
-// Haskell to make a foreign call, or in various other cases when we
-// want to relinquish a Capability that we currently hold.
-//
-// ASSUMES: cap->running_task is the current Task.
-//
-#if defined(THREADED_RTS)
-void releaseCapability (Capability* cap);
-void releaseCapability_ (Capability* cap); // assumes cap->lock is held
-#else
-// releaseCapability() is empty in non-threaded RTS
-INLINE_HEADER void releaseCapability (Capability* cap STG_UNUSED) {};
-INLINE_HEADER void releaseCapability_ (Capability* cap STG_UNUSED) {};
-#endif
-
-#if !IN_STG_CODE
-// one global capability
-extern Capability MainCapability;
-#endif
-
-// Array of all the capabilities
-//
-extern nat n_capabilities;
-extern Capability *capabilities;
-
-// The Capability that was last free. Used as a good guess for where
-// to assign new threads.
-//
-extern Capability *last_free_capability;
-
-// Acquires a capability at a return point. If *cap is non-NULL, then
-// this is taken as a preference for the Capability we wish to
-// acquire.
-//
-// OS threads waiting in this function get priority over those waiting
-// in waitForCapability().
-//
-// On return, *cap is non-NULL, and points to the Capability acquired.
-//
-void waitForReturnCapability (Capability **cap/*in/out*/, Task *task);
-
-INLINE_HEADER void recordMutableCap (StgClosure *p, Capability *cap, nat gen);
-
-#if defined(THREADED_RTS)
-
-// Gives up the current capability IFF there is a higher-priority
-// thread waiting for it. This happens in one of two ways:
-//
-// (a) we are passing the capability to another OS thread, so
-// that it can run a bound Haskell thread, or
-//
-// (b) there is an OS thread waiting to return from a foreign call
-//
-// On return: *pCap is NULL if the capability was released. The
-// current task should then re-acquire it using waitForCapability().
-//
-void yieldCapability (Capability** pCap, Task *task);
-
-// Acquires a capability for doing some work.
-//
-// On return: pCap points to the capability.
-//
-void waitForCapability (Task *task, Mutex *mutex, Capability **pCap);
-
-// Wakes up a thread on a Capability (probably a different Capability
-// from the one held by the current Task).
-//
-void wakeupThreadOnCapability (Capability *cap, StgTSO *tso);
-
-// Wakes up a worker thread on just one Capability, used when we
-// need to service some global event.
-//
-void prodOneCapability (void);
-
-// Similar to prodOneCapability(), but prods all of them.
-//
-void prodAllCapabilities (void);
-
-// Waits for a capability to drain of runnable threads and workers,
-// and then acquires it. Used at shutdown time.
-//
-void shutdownCapability (Capability *cap, Task *task);
-
-// Attempt to gain control of a Capability if it is free.
-//
-rtsBool tryGrabCapability (Capability *cap, Task *task);
-
-#else // !THREADED_RTS
-
-// Grab a capability. (Only in the non-threaded RTS; in the threaded
-// RTS one of the waitFor*Capability() functions must be used).
-//
-extern void grabCapability (Capability **pCap);
-
-#endif /* !THREADED_RTS */
-
-/* -----------------------------------------------------------------------------
- * INLINE functions... private below here
- * -------------------------------------------------------------------------- */
-
-INLINE_HEADER void
-recordMutableCap (StgClosure *p, Capability *cap, nat gen)
-{
- bdescr *bd;
-
- bd = cap->mut_lists[gen];
- if (bd->free >= bd->start + BLOCK_SIZE_W) {
- bdescr *new_bd;
- new_bd = allocBlock_lock();
- new_bd->link = bd;
- bd = new_bd;
- cap->mut_lists[gen] = bd;
- }
- *bd->free++ = (StgWord)p;
-}
-
-#endif /* CAPABILITY_H */
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