3030#include " runtime/task.hpp"
3131#include " runtime/vmOperations.hpp"
3232
33- class VM_QueueHead : public VM_None {
34- public:
35- VM_QueueHead () : VM_None(" QueueHead"
36- };
37-
38- //
39- // Prioritized queue of VM operations.
40- //
41- // Encapsulates both queue management and
42- // and priority policy
43- //
44- class VMOperationQueue : public CHeapObj <mtInternal> {
45- private:
46- enum Priorities {
47- SafepointPriority, // Highest priority (operation executed at a safepoint)
48- MediumPriority, // Medium priority
49- nof_priorities
50- };
51-
52- // We maintain a doubled linked list, with explicit count.
53- int _queue_length[nof_priorities];
54- int _queue_counter;
55- VM_Operation* _queue [nof_priorities];
56-
57- static VM_QueueHead _queue_head[nof_priorities];
58-
59- // Double-linked non-empty list insert.
60- void insert (VM_Operation* q,VM_Operation* n);
61- void unlink (VM_Operation* q);
62-
63- // Basic queue manipulation
64- bool queue_empty (int prio);
65- void queue_add (int prio, VM_Operation *op);
66- VM_Operation* queue_remove_front (int prio);
67- // lock-free query: may return the wrong answer but must not break
68- bool queue_peek (int prio) { return _queue_length[prio] > 0 ; }
69-
70- public:
71- VMOperationQueue ();
72-
73- // Highlevel operations. Encapsulates policy
74- void add (VM_Operation *op);
75- VM_Operation* remove_next (); // Returns next or null
76- bool peek_at_safepoint_priority () { return queue_peek (SafepointPriority); }
77- };
78-
79-
8033// VM operation timeout handling: warn or abort the VM when VM operation takes
8134// too long. Periodic tasks do not participate in safepoint protocol, and therefore
8235// can fire when application threads are stopped.
@@ -114,9 +67,12 @@ class VMThread: public NamedThread {
11467
11568 static VMOperationTimeoutTask* _timeout_task;
11669
117- static VM_Operation* no_op_safepoint ();
70+ static bool handshake_alot ();
71+ static void setup_periodic_safepoint_if_needed ();
11872
11973 void evaluate_operation (VM_Operation* op);
74+ void inner_execute (VM_Operation* op);
75+ void wait_for_operation ();
12076
12177 public:
12278 // Constructor
@@ -143,16 +99,26 @@ class VMThread: public NamedThread {
14399 static void execute (VM_Operation* op);
144100
145101 // Returns the current vm operation if any.
146- static VM_Operation* vm_operation () { return _cur_vm_operation; }
147- static VM_Operation::VMOp_Type vm_op_type () { return _cur_vm_operation->type (); }
102+ static VM_Operation* vm_operation () {
103+ assert (Thread::current ()->is_VM_thread (), " Must be"
104+ return _cur_vm_operation;
105+ }
106+
107+ static VM_Operation::VMOp_Type vm_op_type () {
108+ VM_Operation* op = vm_operation ();
109+ assert (op != NULL , " sanity"
110+ return op->type ();
111+ }
148112
149113 // Returns the single instance of VMThread.
150114 static VMThread* vm_thread () { return _vm_thread; }
151115
152116 void verify ();
153117
154118 // Performance measurement
155- static PerfCounter* perf_accumulated_vm_operation_time () { return _perf_accumulated_vm_operation_time; }
119+ static PerfCounter* perf_accumulated_vm_operation_time () {
120+ return _perf_accumulated_vm_operation_time;
121+ }
156122
157123 // Entry for starting vm thread
158124 virtual void run ();
@@ -161,10 +127,14 @@ class VMThread: public NamedThread {
161127 static void create ();
162128 static void destroy ();
163129
130+ static void wait_until_executed (VM_Operation* op);
131+
164132 private:
165133 // VM_Operation support
166134 static VM_Operation* _cur_vm_operation; // Current VM operation
167- static VMOperationQueue* _vm_queue; // Queue (w/ policy) of VM operations
135+ static VM_Operation* _next_vm_operation; // Next VM operation
136+
137+ bool set_next_operation (VM_Operation *op); // Set the _next_vm_operation if possible.
168138
169139 // Pointer to single-instance of VM thread
170140 static VMThread* _vm_thread;
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