X-Git-Url: http://demsky.eecs.uci.edu/git/?p=model-checker-benchmarks.git;a=blobdiff_plain;f=concurrent-hashmap%2Fhashmap.h;fp=concurrent-hashmap%2Fhashmap.h;h=0d249251ec99dcaabbd10d301df8873a5f3a9cc1;hp=0000000000000000000000000000000000000000;hb=3cb559e8fea6c3839ed20d6a10a636d728cf8695;hpb=c046bae812a0dd4d54be2236487c112d36641538

diff --git a/concurrent-hashmap/hashmap.h b/concurrent-hashmap/hashmap.h
new file mode 100644
index 0000000..0d24925
--- /dev/null
+++ b/concurrent-hashmap/hashmap.h
@@ -0,0 +1,308 @@
+#ifndef _HASHMAP_H
+#define _HASHMAP_H
+
+#include <iostream>
+#include <atomic>
+#include "stdio.h" 
+//#include <common.h>
+#ifdef STANDALONE
+#include <assert.h>
+#define MODEL_ASSERT assert 
+#else
+#include <model-assert.h>
+#endif
+#include <stdlib.h>
+#include <mutex>
+
+#include "common.h"
+#include "sc_annotation.h"
+
+#define relaxed memory_order_relaxed
+#define release memory_order_release
+#define acquire memory_order_acquire
+#define acq_rel memory_order_acq_rel
+#define seq_cst memory_order_seq_cst
+
+using namespace std;
+
+/**
+	For the sake of simplicity, we do not use template but some toy structs to
+	represent the Key and Value.
+*/
+struct Key {
+	// Probably represent the coordinate (x, y, z)
+	int x;
+	int y;
+	int z;
+
+	int hashCode() {
+		return x + 31 * y + 31 * 31 * z;
+	}
+
+	bool equals(Key *other) {
+		if (!other)
+			return false;
+		return x == other->x && y == other->y && z == other->z;
+	}
+
+	Key(int x, int y, int z) :
+		x(x),
+		y(y),
+		z(z)
+	{
+
+	}
+};
+
+struct Value {
+	// Probably represent the speed vector (vX, vY, vZ)
+	int vX;
+	int vY;
+	int vZ;
+
+	Value(int vX, int vY, int vZ) :
+		vX(vX),
+		vY(vY),
+		vZ(vZ)
+	{
+
+	}
+
+	bool equals(Value *other) {
+		if (!other)
+			return false;
+		return vX == other->vX && vY == other->vY && vZ == other->vZ;
+	}
+};
+
+class Entry {
+	public:
+	Key *key;
+	atomic<Value*> value;
+	int hash;
+	atomic<Entry*> next;
+
+	Entry(int h, Key *k, Value *v, Entry *n) {
+		this->hash = h;
+		this->key = k;
+		this->value.store(v, relaxed);
+		this->next.store(n, relaxed);
+	}
+};
+
+class Segment {
+	public:
+	int count;
+	mutex segMutex;
+
+	void lock() {
+		segMutex.lock();
+	}
+
+	void unlock() {
+		segMutex.unlock();
+	}
+
+	Segment() {
+		this->count = 0;
+	}
+};
+
+class HashMap {
+	public:
+	atomic<Entry*> *table;
+
+	int capacity;
+	int size;
+
+	static const int CONCURRENCY_LEVEL = 16;
+
+	static const int SEGMENT_MASK = CONCURRENCY_LEVEL - 1;
+
+	Segment *segments[CONCURRENCY_LEVEL];
+
+	static const int DEFAULT_INITIAL_CAPACITY = 16;
+
+	// Not gonna consider resize now...
+	
+	HashMap() {
+		this->size = 0;
+		this->capacity = DEFAULT_INITIAL_CAPACITY;
+		this->table = new atomic<Entry*>[capacity];
+		for (int i = 0; i < capacity; i++) {
+			atomic_init(&table[i], NULL);
+		}
+		for (int i = 0; i < CONCURRENCY_LEVEL; i++) {
+			segments[i] = new Segment;
+		}
+	}
+
+	int hashKey(Key *x) {
+		int h = x->hashCode();
+		// Use logical right shift
+		unsigned int tmp = (unsigned int) h;
+		return ((h << 7) - h + (tmp >> 9) + (tmp >> 17));
+	}
+
+	bool eq(Key *x, Key *y) {
+		return x == y || x->equals(y);
+	}
+
+	Value* get(Key *key) {
+		MODEL_ASSERT (key);
+		int hash = hashKey(key);
+
+		// Try first without locking...
+		atomic<Entry*> *tab = table;
+		int index = hash & (capacity - 1);
+		atomic<Entry*> *first = &tab[index];
+		Entry *e;
+		Value *res = NULL;
+
+		// Should be a load acquire
+		// This load action here makes it problematic for the SC analysis, what
+		// we need to do is as follows: if the get() method ever acquires the
+		// lock, we ignore this operation for the SC analysis, and otherwise we
+		// take it into consideration
+		
+		SC_BEGIN();
+		Entry *firstPtr = first->load(acquire);
+		SC_END();
+
+		e = firstPtr;
+		while (e != NULL) {
+			if (e->hash == hash && eq(key, e->key)) {
+				res = e->value.load(seq_cst);
+				if (res != NULL)
+					return res;
+				else
+					break;
+			}
+			// Loading the next entry, this can be relaxed because the
+			// synchronization has been established by the load of head
+			e = e->next.load(relaxed);
+		}
+	
+		// Recheck under synch if key apparently not there or interference
+		Segment *seg = segments[hash & SEGMENT_MASK];
+		seg->lock(); // Critical region begins
+		// Not considering resize now, so ignore the reload of table...
+
+		// Synchronized by locking, no need to be load acquire
+		Entry *newFirstPtr = first->load(relaxed);
+		if (e != NULL || firstPtr != newFirstPtr) {
+			e = newFirstPtr;
+			while (e != NULL) {
+				if (e->hash == hash && eq(key, e->key)) {
+					// Protected by lock, no need to be SC
+					res = e->value.load(relaxed);
+					seg->unlock(); // Critical region ends
+					return res;
+				}
+				// Synchronized by locking
+				e = e->next.load(relaxed);
+			}
+		}
+		seg->unlock(); // Critical region ends
+		return NULL;
+	}
+
+	Value* put(Key *key, Value *value) {
+		// Don't allow NULL key or value
+		MODEL_ASSERT (key && value);
+
+		int hash = hashKey(key);
+		Segment *seg = segments[hash & SEGMENT_MASK];
+		atomic<Entry*> *tab;
+
+		seg->lock(); // Critical region begins
+		tab = table;
+		int index = hash & (capacity - 1);
+
+		atomic<Entry*> *first = &tab[index];
+		Entry *e;
+		Value *oldValue = NULL;
+	
+		// The written of the entry is synchronized by locking
+		Entry *firstPtr = first->load(relaxed);
+		e = firstPtr;
+		while (e != NULL) {
+			if (e->hash == hash && eq(key, e->key)) {
+				// FIXME: This could be a relaxed (because locking synchronize
+				// with the previous put())??  no need to be acquire
+				oldValue = e->value.load(relaxed);
+				e->value.store(value, seq_cst);
+				seg->unlock(); // Don't forget to unlock before return
+				return oldValue;
+			}
+			// Synchronized by locking
+			e = e->next.load(relaxed);
+		}
+
+		// Add to front of list
+		Entry *newEntry = new Entry(hash, key, value, firstPtr);
+		// Publish the newEntry to others
+		first->store(newEntry, release);
+		seg->unlock(); // Critical region ends
+		return NULL;
+	}
+
+	Value* remove(Key *key, Value *value) {
+		MODEL_ASSERT (key);
+		int hash = hashKey(key);
+		Segment *seg = segments[hash & SEGMENT_MASK];
+		atomic<Entry*> *tab;
+
+		seg->lock(); // Critical region begins
+		tab = table;
+		int index = hash & (capacity - 1);
+
+		atomic<Entry*> *first = &tab[index];
+		Entry *e;
+		Value *oldValue = NULL;
+	
+		// The written of the entry is synchronized by locking
+		Entry *firstPtr = first->load(relaxed);
+		e = firstPtr;
+
+		while (true) {
+			if (e != NULL) {
+				seg->unlock(); // Don't forget to unlock
+				return NULL;
+			}
+			if (e->hash == hash && eq(key, e->key))
+				break;
+			// Synchronized by locking
+			e = e->next.load(relaxed);
+		}
+
+		// FIXME: This could be a relaxed (because locking synchronize
+		// with the previous put())?? No need to be acquire
+		oldValue = e->value.load(relaxed);
+		// If the value parameter is NULL, we will remove the entry anyway
+		if (value != NULL && value->equals(oldValue)) {
+			seg->unlock();
+			return NULL;
+		}
+
+		// Force the get() to grab the lock and retry
+		e->value.store(NULL, relaxed);
+
+		// The strategy to remove the entry is to keep the entries after the
+		// removed one and copy the ones before it
+		Entry *head = e->next.load(relaxed);
+		Entry *p;
+		p = first->load(relaxed);
+		while (p != e) {
+			head = new Entry(p->hash, p->key, p->value.load(relaxed), head);
+			p = p->next.load(relaxed);
+		}
+
+		// Publish the new head to readers 
+		first->store(head, release);
+		seg->unlock(); // Critical region ends
+		return oldValue;
+	}
+};
+
+#endif