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Added CRTurn and CRHandover #1

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135 changes: 135 additions & 0 deletions CorreiaRamalheteHandover.c
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// Correia and Ramalhete CRHandover, Mutual Exclusion - Two linear wait software solutions
// https://github.com/pramalhe/ConcurrencyFreaks/tree/master/papers/cralgorithm-2015.pdf
//
// Shared words = 2N+1
// Number of states = 3 + 2
// Starvation-Free = yes, with N
// Minimum SC stores = 1 + 1
// Minimum SC loads = 2 + 2

enum Intent { UNLOCKED, WAITING, LOCKED };
enum Handover { NOTMINE, MYTURN };

static volatile TYPE *states CALIGN; // shared
static volatile TYPE *handover CALIGN; // shared
static volatile TYPE hoEnabled CALIGN; // shared

inline static const int validate_left(const int id) {
for (int i = 0; i < id; i++) {
if (states[i] != UNLOCKED) return 0;
}
return 1;
}

inline static const int validate_right(const int id) {
for (int i = id + 1; i < N; i++) {
if (states[i] == LOCKED) return 0;
}
return 1;
}

static void *Worker( void *arg ) {
TYPE id = (size_t)arg;
uint64_t entry;
#ifdef FAST
unsigned int cnt = 0, oid = id;
#endif // FAST

for ( int r = 0; r < RUNS; r += 1 ) {
entry = 0;
while ( stop == 0 ) {
int i, isFirstTime = 1;
while (1) {
while (hoEnabled) {
if (isFirstTime) { states[id] = WAITING; Fence(); isFirstTime = 0; }
if (handover[id] == MYTURN) {
handover[id] = NOTMINE;
states[id] = LOCKED;
goto LCS; // fast-path under high contention
}
Pause();
}
isFirstTime = 0;
states[id] = LOCKED;
Fence();
for (i = 0; i < id; i++) {
if (states[i] != UNLOCKED) break;
}
if (i != id) {
states[id] = WAITING;
Fence();
while (!hoEnabled) {
for (i = 0; i < id; i++) {
if (states[i] != UNLOCKED) break;
}
if (i == id) break;
Pause();
}
continue;
}
while (!hoEnabled) {
for (i = id + 1; i < N; i++) {
if (states[i] == LOCKED) break;
}
if (i == N && !hoEnabled) goto LCS;
}
states[id] = WAITING;
Fence();
}
LCS: CriticalSection( id ); // critical section
for (int i = id + 1; i < N; i++) {
if (states[i] == WAITING) {
if (!hoEnabled) hoEnabled = 1;
handover[i] = MYTURN;
states[id] = UNLOCKED;
goto LEND;
}
}
for (int i = 0; i < id; i++) {
if (states[i] == WAITING) {
if (!hoEnabled) hoEnabled = 1;
handover[i] = MYTURN;
states[id] = UNLOCKED;
goto LEND;
}
}
// There are no successors at all
if (hoEnabled) hoEnabled = 0;
states[id] = UNLOCKED;
LEND:
#ifdef FAST
id = startpoint( cnt ); // different starting point each experiment
cnt = cycleUp( cnt, NoStartPoints );
#endif // FAST
entry += 1;
} // while
#ifdef FAST
id = oid;
#endif // FAST
entries[r][id] = entry;
__sync_fetch_and_add( &Arrived, 1 );
while ( stop != 0 ) Pause();
__sync_fetch_and_add( &Arrived, -1 );
} // for
return NULL;
} // Worker

void ctor() {
states = Allocator( sizeof(typeof(states[0])) * N );
handover = Allocator( sizeof(typeof(handover[0])) * N );
for ( int i = 0; i < N; i += 1 ) { // initialize shared data
states[i] = UNLOCKED;
handover[i] = NOTMINE;
} // for
hoEnabled = 0; // false
} // ctor

void dtor() {
free( (void *)states );
free( (void *)handover );
} // dtor

// Local Variables: //
// tab-width: 4 //
// compile-command: "gcc -Wall -std=gnu99 -O3 -DNDEBUG -fno-reorder-functions -DPIN -DAlgorithm=CorreiaRamalheteHandover Harness.c -lpthread -lm" //
// End: //
116 changes: 116 additions & 0 deletions CorreiaRamalheteTurn.c
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// Correia and Ramalhete CRTurn, Mutual Exclusion - Two linear wait software solutions
// https://github.com/pramalhe/ConcurrencyFreaks/tree/master/papers/cralgorithm-2015.pdf
//
// Shared words = N+1
// Number of states = 3
// Starvation-Free = yes, with N
// Minimum SC stores = 1 + 1
// Minimum SC loads = N+2

enum Intent { UNLOCKED, WAITING, LOCKED };

static volatile TYPE *states CALIGN; // shared
static volatile TYPE turn CALIGN; // shared

inline static const int validate_left(const int id, const int lturn) {
int i;
if (lturn > id) {
for (i = lturn; i < N; i++) {
if (states[i] != UNLOCKED) return 0;
}
for (i = 0; i < id; i++) {
if (states[i] != UNLOCKED) return 0;
}
} else {
for (i = lturn; i < id; i++) {
if (states[i] != UNLOCKED) return 0;
}
}
return 1;
}

inline static const int validate_right(const int id, const int lturn) {
int i;
if (lturn <= id) {
for (i = id + 1; i < N; i++) {
if (states[i] == LOCKED) return 0;
}
for (i = 0; i < lturn; i++) {
if (states[i] == LOCKED) return 0;
}
} else {
for (i = id + 1; i < lturn; i++) {
if (states[i] == LOCKED) return 0;
}
}
return 1;
}

static void *Worker( void *arg ) {
TYPE id = (size_t)arg;
uint64_t entry;
#ifdef FAST
unsigned int cnt = 0, oid = id;
#endif // FAST

for ( int r = 0; r < RUNS; r += 1 ) {
entry = 0;
while ( stop == 0 ) {
states[id] = LOCKED;
Fence();
while (1) {
TYPE lturn = turn;
if (!validate_left(id, lturn)) {
states[id] = WAITING;
Fence();
while (1) {
if (validate_left(id, lturn) && lturn == turn) break;
Pause();
lturn = turn;
}
states[id] = LOCKED;
Fence();
continue;
}
while (lturn == turn) {
if (validate_right(id, lturn)) break;
Pause();
}
if (lturn == turn) break;
}
CriticalSection( id ); // critical section
turn = (turn+1) % N;
states[id] = UNLOCKED; // exit protocol
#ifdef FAST
id = startpoint( cnt ); // different starting point each experiment
cnt = cycleUp( cnt, NoStartPoints );
#endif // FAST
entry += 1;
} // while
#ifdef FAST
id = oid;
#endif // FAST
entries[r][id] = entry;
__sync_fetch_and_add( &Arrived, 1 );
while ( stop != 0 ) Pause();
__sync_fetch_and_add( &Arrived, -1 );
} // for
return NULL;
} // Worker

void ctor() {
states = Allocator( sizeof(typeof(states[0])) * N );
for ( int i = 0; i < N; i += 1 ) { // initialize shared data
states[i] = UNLOCKED;
} // for
turn = 0;
} // ctor

void dtor() {
free( (void *)states );
} // dtor

// Local Variables: //
// tab-width: 4 //
// compile-command: "gcc -Wall -std=gnu99 -O3 -DNDEBUG -fno-reorder-functions -DPIN -DAlgorithm=CorreiaRamalheteTurn Harness.c -lpthread -lm" //
// End: //