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This is mostly working around a bad compiler optimization. The Intel 80386 processor introduced some bit operations that would be the perfect translation for atomic single-bit read-modify-and-write operations. Alas, even the latest compilers as of today (GCC 11, clang 13, Microsoft Visual C 19.29) would generate a loop around LOCK CMPXCHG instead of emitting the instructions LOCK BTS (fetch_or()), LOCK BTR (fetch_and()), LOCK BTC (fetch_xor()). fil_space_t::clear_closing(): Clear the CLOSING flag. fil_space_t::set_stopping_check(): Special variant of fil_space_t::set_stopping() that will return the old value of the STOPPING flag after atomically setting it. fil_space_t::clear_stopping(): Use fetch_sub() to toggle the STOPPING flag. The flag is guaranteed to be set upon calling this function, hence we will toggle it to clear it. On IA-32 and AMD64, this will translate into the 80486 LOCK XADD instruction. fil_space_t::check_pending_operations(): Replace a Boolean variable with a goto label, to allow more compact code generation for fil_space_t::set_stopping_check(). trx_rseg_t: Define private accessors ref_set() and ref_reset() for setting and clearing the flags. trx_lock_t::clear_deadlock_victim(), trx_lock_t::set_wsrep_victim(): Accessors for clearing and setting the flags. |
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| .. | ||
| fil0crypt.cc | ||
| fil0fil.cc | ||
| fil0pagecompress.cc | ||