From 4ecf7917ccc7c345388e85946444e8ab29e3c5f7 Mon Sep 17 00:00:00 2001 From: Joel Dice Date: Sat, 2 Jun 2007 20:00:23 -0600 Subject: [PATCH] sketch Machine and Thread classes; refine allocation and thread state transitions --- src/vm.cpp | 252 +++++++++++++++++++++++++++++++++++++++++++---------- 1 file changed, 208 insertions(+), 44 deletions(-) diff --git a/src/vm.cpp b/src/vm.cpp index 3696a69569..5278801e6e 100644 --- a/src/vm.cpp +++ b/src/vm.cpp @@ -1,8 +1,94 @@ +#include "common.h" +#include "system.h" +#include "heap.h" + namespace { +typedef void* object; + +class Thread; + +class Machine { + public: + System* sys; + Heap* heap; + Thread* rootThread; + Thread* exclusive; + unsigned activeCount; + unsigned liveCount; + System::Monitor* stateLock; +}; + +class Thread { + public: + enum State { + NoState, + ActiveState, + IdleState, + ZombieState, + ExclusiveState, + ExitState + }; + + static const unsigned HeapSize = 64 * 1024; + static const unsigned StackSize = 64 * 1024; + + Machine* vm; + Thread* next; + Thread* child; + State state; + object frame; + object code; + object exception; + unsigned sp; + unsigned heapIndex; + object stack[StackSize]; + object heap[HeapSize]; +}; + +inline void NO_RETURN +abort(Thread* t) +{ + t->vm->sys->abort(); +} + +inline void +assert(Thread* t, bool v) +{ + if (UNLIKELY(not v)) abort(t); +} + +void +init(Machine* m, System* sys, Heap* heap) +{ + sys->zero(m, sizeof(Machine)); + m->sys = sys; + m->heap = heap; + if (not sys->success(sys->make(&(m->stateLock)))) { + sys->abort(); + } +} + +void +dispose(Machine* m) +{ + m->stateLock->dispose(); +} + +void +init(Thread* t, Machine* m) +{ + m->sys->zero(m, sizeof(Thread)); + t->vm = m; + m->rootThread = t; + t->state = Thread::NoState; +} + void iterate(Thread* t, Heap::Visitor* v) { + t->heapIndex = 0; + v->visit(&(t->frame)); v->visit(&(t->code)); v->visit(&(t->exception)); @@ -33,64 +119,144 @@ collect(Machine* m, Heap::CollectionType type) Machine* machine; } it(m); - m->heap.collect(type, &it); + m->heap->collect(type, &it); } -object -collectAndAllocate(Thread* t, unsigned size) +void +enter(Thread* t, Thread::State s) { - if (size > Thread::HeapSize) { - abort(); // not yet implemented - } + if (s == state) return; - LOCK(t->vm->stateLock); + ACQUIRE(t->vm->stateLock); - if (t->vm->exclusive) { - // enter idle state and wait for collection to finish. - t->state = Thread::IdleState; - -- t->vm->activeCount; - - t->vm->stateLock->notifyAll(); + switch (s) { + case ExclusiveState: { + assert(t, state == ActiveState); while (t->vm->exclusive) { - t->vm->stateLock->wait(); + // another thread got here first. + enter(t, Thread::IdleState); + enter(t, Thread::ActiveState); } - // wake up. - state = Thread::ActiveState; - ++ t->vm->activeCount; - } else { - // enter exclusive state and wait for other threads to go idle. + t->state = ExclusiveState; t->vm->exclusive = t; - + while (t->vm->activeCount > 1) { t->vm->stateLock->wait(); } + } break; - // collect. - collect(t->vm, Heap::MinorCollection); + case IdleState: + case ZombieState: { + switch (state) { + case ExclusiveState: { + assert(t, t->vm->exclusive == t); + t->vm->exclusive = 0; + } break; + + case ActiveState: break; + + default: abort(t); + } + + -- t->vm->activeCount; + if (s == ZombieState) { + -- t->vm->liveCount; + } + t->state = s; - // signal collection finish. - t->vm->exclusive = 0; t->vm->stateLock->notifyAll(); + } break; + + case ActiveState: { + switch (state) { + case ExclusiveState: { + assert(t, t->vm->exclusive == t); + + t->state = s; + t->vm->exclusive = 0; + + t->vm->stateLock->notifyAll(); + } break; + + case NoState: + case IdleState: { + while (t->vm->exclusive) { + t->vm->stateLock->wait(); + } + + ++ t->vm->activeCount; + if (state == NoState) { + ++ t->vm->liveCount; + } + t->state = s; + } break; + + default: abort(t); + } + } break; + + case ExitState: { + switch (state) { + case ExclusiveState: { + assert(t, t->vm->exclusive == t); + t->vm->exclusive = 0; + } break; + + case ActiveState: break; + + default: abort(t); + } + + -- t->vm->activeCount; + t->state = s; + + while (t->vm->liveCount > 1) { + t->vm->stateLock->wait(); + } + } break; + + default: abort(t); + } +} + +void +maybeYieldAndMaybeCollect(Thread* t, unsigned size) +{ + if (size > Thread::HeapSize) { + // large object support not yet implemented. + abort(t); } - t->heapIndex += size; - return t->heap; + ACQUIRE(t->vm->stateLock); + + while (t->vm->exclusive) { + // another thread wants to enter the exclusive state, either for a + // collection or some other reason. We give it a chance here. + enter(t, Thread::IdleState); + enter(t, Thread::ActiveState); + } + + if (t->heapIndex + size >= Thread::HeapSize) { + enter(t, Thread::ExclusiveState); + collect(t->vm, Heap::MinorCollection); + enter(t, Thread::ActiveState); + } } inline object allocate(Thread* t, unsigned size) { - if (UNLIKELY(size > Thread::HeapSize - t->heapIndex + if (UNLIKELY(t->heapIndex + size >= Thread::HeapSize or t->vm->exclusive)) { - return collectAndAllocate(t, size); - } else { - object o = t->heap + t->heapIndex; - t->heapIndex += size; - return o; + maybeYieldAndMaybeCollect(t, size); } + + object o = t->heap + t->heapIndex; + t->heapIndex += size; + return o; } object @@ -192,7 +358,7 @@ run(Thread* t) if (t->exception) goto throw_; object array = makeObjectArray(t, class_, c); - memset(objectArrayBody(array), 0, c * 4); + t->vm->sys->zero(objectArrayBody(array), c * 4); PUSH(array); } else { @@ -225,7 +391,7 @@ run(Thread* t) t->exception = makeNullPointerException(t, 0); goto throw_; } - } UNREACHABLE; + } abort(t); case astore: case istore: @@ -268,7 +434,7 @@ run(Thread* t) t->exception = makeNullPointerException(t, 0); } goto throw_; - } UNREACHABLE; + } abort(t); case baload: { object index; POP(index); @@ -1182,9 +1348,8 @@ run(Thread* t) unsigned size = instanceSize(class_); object instance = allocate(t, size); *static_cast(instance) = class_; - memset(static_cast(instance) + sizeof(object), - 0, - size - sizeof(object)); + t->vm->sys->zero(static_cast(instance) + sizeof(object), + size - sizeof(object)); PUSH(instance); } goto loop; @@ -1240,12 +1405,11 @@ run(Thread* t) factor = 8; break; - default: UNREACHABLE; + default: abort(t); } - memset(static_cast(instance) + (sizeof(object) * 2), - 0, - c * factor); + t->vm->sys->zero(static_cast(instance) + (sizeof(object) * 2), + c * factor); PUSH(array); } else { @@ -1379,7 +1543,7 @@ run(Thread* t) case wide: goto wide; - default: UNREACHABLE; + default: abort(t); } wide: @@ -1423,7 +1587,7 @@ run(Thread* t) ip = intValue(frameBody(t->frame)[(index1 << 8) | index2]); } goto loop; - default: UNREACHABLE; + default: abort(t); } invoke: