[SNAPSHOT]:
* Rename functions get_produced / get_consummed into get_write_buffer and get_read_buffer * Add function _updated_p * Add comments.
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Patrick Pelissier committed
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49624eee15
commit
2700ccba1a
3 files changed
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-18
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@@ -93,18 +93,24 @@
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//defered
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#define SNAPSHOTI_DEF(arg) SNAPSHOTI_DEF2 arg
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// This is basically an atomic triple buffer between a produced thread
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// and a consummer thread.
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// TODO: Analyse generalisation to N produced threads and M consummer threads
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#define SNAPSHOTI_MAX_BUFFER 3
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#define SNAPSHOTI_DEF2(name, type, oplist) \
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\
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typedef struct M_C(name, _s) { \
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type data[3]; \
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type data[SNAPSHOTI_MAX_BUFFER]; \
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atomic_uchar flags; \
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} M_C(name, _t)[1]; \
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\
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typedef type M_C(name, _type_t); \
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\
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static inline void M_C(name, _init)(M_C(name, _t) snap) \
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{ \
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assert(snap != NULL); \
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for(int i = 0; i < 3; i++) { \
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for(int i = 0; i < SNAPSHOTI_MAX_BUFFER; i++) { \
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M_GET_INIT oplist(snap->data[i]); \
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} \
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atomic_init (&snap->flags, SNAPSHOTI_FLAG(0, 1, 2, 0)); \
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@@ -114,7 +120,7 @@
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static inline void M_C(name, _clear)(M_C(name, _t) snap) \
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{ \
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SNAPSHOTI_CONTRACT(snap); \
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for(int i = 0; i < 3; i++) { \
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for(int i = 0; i < SNAPSHOTI_MAX_BUFFER; i++) { \
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M_GET_CLEAR oplist(snap->data[i]); \
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} \
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} \
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@@ -124,7 +130,7 @@
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{ \
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SNAPSHOTI_CONTRACT(org); \
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assert(snap != NULL && snap != org); \
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for(int i = 0; i < 3; i++) { \
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for(int i = 0; i < SNAPSHOTI_MAX_BUFFER; i++) { \
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M_GET_INIT_SET oplist(snap->data[i], org->data[i]); \
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} \
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atomic_init (&snap->flags, atomic_load(&org->flags)); \
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@@ -136,7 +142,7 @@
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{ \
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SNAPSHOTI_CONTRACT(snap); \
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SNAPSHOTI_CONTRACT(org); \
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for(int i = 0; i < 3; i++) { \
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for(int i = 0; i < SNAPSHOTI_MAX_BUFFER; i++) { \
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M_GET_SET oplist(snap->data[i], org->data[i]); \
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} \
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atomic_init (&snap->flags, atomic_load(&org->flags)); \
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@@ -149,7 +155,7 @@
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{ \
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SNAPSHOTI_CONTRACT(org); \
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assert(snap != NULL && snap != org); \
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for(int i = 0; i < 3; i++) { \
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for(int i = 0; i < SNAPSHOTI_MAX_BUFFER; i++) { \
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M_GET_INIT_MOVE oplist(snap->data[i], org->data[i]); \
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} \
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snap->flags = org->flags; \
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@@ -165,7 +171,7 @@
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SNAPSHOTI_CONTRACT(snap); \
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SNAPSHOTI_CONTRACT(org); \
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assert(snap != org); \
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for(int i = 0; i < 3; i++) { \
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for(int i = 0; i < SNAPSHOTI_MAX_BUFFER; i++) { \
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M_GET_MOVE oplist(snap->data[i], org->data[i]); \
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} \
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snap->flags = org->flags; \
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@@ -174,17 +180,21 @@
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} \
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,) /* IF_METHOD (MOVE) */ \
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\
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\
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static inline type *M_C(name, _take)(M_C(name, _t) snap) \
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{ \
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SNAPSHOTI_CONTRACT(snap); \
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unsigned char nextFlags, origFlags = atomic_load (&snap->flags); \
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/* Atomic CAS operation */ \
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do { \
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/* Swap F and W buffer, setting exchange flag */ \
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nextFlags = SNAPSHOTI_FLAG(SNAPSHOTI_R(origFlags), \
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SNAPSHOTI_F(origFlags), \
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SNAPSHOTI_W(origFlags), 1); \
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/* TODO: exponential backoff */ \
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/* FIXME: Is exponential backoff really needed ? */ \
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} while (!atomic_compare_exchange_weak (&snap->flags, &origFlags, \
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nextFlags)); \
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/* Return new write buffer for new updating */ \
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return &snap->data[SNAPSHOTI_W(nextFlags)]; \
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} \
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\
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@@ -192,27 +202,39 @@
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{ \
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SNAPSHOTI_CONTRACT(snap); \
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unsigned char nextFlags, origFlags = atomic_load (&snap->flags); \
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/* Atomic CAS operation */ \
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do { \
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if (!SNAPSHOTI_B(origFlags)) \
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/* If no exchange registered, do nothing and keep the same */ \
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if (!SNAPSHOTI_B(origFlags)) { \
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nextFlags = origFlags; \
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break; \
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} \
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/* Swap R and F buffer, clearing exchange flag */ \
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nextFlags = SNAPSHOTI_FLAG(SNAPSHOTI_F(origFlags), \
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SNAPSHOTI_W(origFlags), \
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SNAPSHOTI_R(origFlags), 0); \
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/* TODO: exponential backoff */ \
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/* FIXME: Is exponential backoff really needed ? */ \
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} while (!atomic_compare_exchange_weak (&snap->flags, &origFlags, \
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nextFlags)); \
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nextFlags = atomic_load(&snap->flags); \
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/* Return current read buffer */ \
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return M_CONST_CAST(type, &snap->data[SNAPSHOTI_R(nextFlags)]); \
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} \
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\
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static inline type *M_C(name, _get_produced)(M_C(name, _t) snap) \
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static inline bool M_C(name, _updated_p)(M_C(name, _t) snap) \
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{ \
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SNAPSHOTI_CONTRACT(snap); \
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unsigned char flags = atomic_load (&snap->flags); \
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return SNAPSHOTI_B(flags); \
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} \
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\
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static inline type *M_C(name, _get_write_buffer)(M_C(name, _t) snap) \
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{ \
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SNAPSHOTI_CONTRACT(snap); \
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unsigned char flags = atomic_load(&snap->flags); \
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return &snap->data[SNAPSHOTI_W(flags)]; \
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} \
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\
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static inline const type *M_C(name, _get_consummed)(M_C(name, _t) snap) \
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static inline const type *M_C(name, _get_read_buffer)(M_C(name, _t) snap) \
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{ \
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SNAPSHOTI_CONTRACT(snap); \
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unsigned char flags = atomic_load(&snap->flags); \
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