1 /* Copyright (C) 2006,2007 MySQL AB 2 3 This program is free software; you can redistribute it and/or modify 4 it under the terms of the GNU General Public License as published by 5 the Free Software Foundation; version 2 of the License. 6 7 This program is distributed in the hope that it will be useful, 8 but WITHOUT ANY WARRANTY; without even the implied warranty of 9 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 10 GNU General Public License for more details. 11 12 You should have received a copy of the GNU General Public License 13 along with this program; if not, write to the Free Software 14 Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1335 USA */ 15 16 /* 17 WL#3071 Maria checkpoint 18 First version written by Guilhem Bichot on 2006-04-27. 19 Does not compile yet. 20 */ 21 22 /* This is the interface of this module. */ 23 24 typedef enum enum_ma_checkpoint_level { 25 CHECKPOINT_NONE= 0, 26 /* just write dirty_pages, transactions table and sync files */ 27 CHECKPOINT_INDIRECT, 28 /* also flush all dirty pages which were already dirty at prev checkpoint */ 29 CHECKPOINT_MEDIUM, 30 /* also flush all dirty pages */ 31 CHECKPOINT_FULL 32 } CHECKPOINT_LEVEL; 33 34 C_MODE_START 35 int ma_checkpoint_init(ulong interval); 36 void ma_checkpoint_end(void); 37 int ma_checkpoint_execute(CHECKPOINT_LEVEL level, my_bool no_wait); 38 C_MODE_END 39 40 /** 41 @brief reads some LSNs with special trickery 42 43 If a 64-bit variable transitions between both halves being zero to both 44 halves being non-zero, and back, this function can be used to do a read of 45 it (without mutex, without atomic load) which always produces a correct 46 (though maybe slightly old) value (even on 32-bit CPUs). The value is at 47 least as new as the latest mutex unlock done by the calling thread. 48 The assumption is that the system sets both 4-byte halves either at the 49 same time, or one after the other (in any order), but NOT some bytes of the 50 first half then some bytes of the second half then the rest of bytes of the 51 first half. With this assumption, the function can detect when it is 52 seeing an inconsistent value. 53 54 @param LSN pointer to the LSN variable to read 55 56 @return LSN part (most significant byte always 0) 57 */ 58 #if ( SIZEOF_CHARP >= 8 ) 59 /* 64-bit CPU, 64-bit reads are atomic */ 60 #define lsn_read_non_atomic LSN_WITH_FLAGS_TO_LSN 61 #else 62 static inline LSN lsn_read_non_atomic_32(const volatile LSN *x) 63 { 64 /* 65 32-bit CPU, 64-bit reads may give a mixed of old half and new half (old 66 low bits and new high bits, or the contrary). 67 */ 68 for (;;) /* loop until no atomicity problems */ 69 { 70 /* 71 Remove most significant byte in case this is a LSN_WITH_FLAGS object. 72 Those flags in TRN::first_undo_lsn break the condition on transitions so 73 they must be removed below. 74 */ 75 LSN y= LSN_WITH_FLAGS_TO_LSN(*x); 76 if (likely((y == LSN_IMPOSSIBLE) || LSN_VALID(y))) 77 return y; 78 } 79 } 80 #define lsn_read_non_atomic(x) lsn_read_non_atomic_32(&x) 81 #endif 82 83 /** 84 prints a message from a task not connected to any user (checkpoint 85 and recovery for example). 86 87 @param level 0 if error, ME_WARNING if warning, 88 ME_NOTE if info 89 @param sentence text to write 90 */ 91 #define ma_message_no_user(level, sentence) \ 92 my_printf_error(HA_ERR_GENERIC, "Aria engine: %s", MYF(level), sentence) 93