Collaboration diagram for pin_i:
Certain operations on the records referenced by a pin_i may invalidate the pin_i. For example, if you pin a record, then truncate it or append to it while holding a pin_i, the pin_i must be considered invalidated because appending to the record might necessarily require moving it.
The pin functions take a lock mode parameter that tells the storage manager how to lock the record initially. The options are SH and EX. EX should be used when the pinned record will be updated (through update_rec, unpdate_rec_hdr, append_rec, or truncate_rec). Using EX in these cases will improve performance and reduce the risk of deadlock, but it is not necessary for correctness.
If you pin with SH, and subsequently modify the record through pin_i, the pin_i method(s) will upgrade locks as necessary to maintain ACID properties.
These methods will not perform needless unfix/refix operations: you may pin many small records on the same page in sequence and avoid unfixing the page between pins.
Definition at line 184 of file pin.h.
Public Member Functions | |
| NORET | pin_i () |
| Constructor. Does not pin anything until pin() is called. | |
| NORET | ~pin_i () |
| Destructor. Unpins anything currently pinned. | |
| rc_t | pin (const rid_t &rid, smsize_t start, lock_mode_t lmode=SH) |
| Pin a portion of the record starting at a given location. | |
| rc_t | pin (const rid_t &rid, smsize_t start, lock_mode_t lock_mode, latch_mode_t latch_mode) |
| Pin a portion of the record starting at a given location. | |
| void | unpin () |
| Unpin whatever record was pinned. | |
| bool | is_mine () const |
| True if the running thread owns this pin_i. | |
| void | set_ref_bit (int value) |
| Set the reference bit to use for the buffer frame containing the pinned body page when the page is unpinned. | |
| rc_t | repin (lock_mode_t lmode=SH) |
| Efficiently repin a record after is size has changed or after it has been unpinned. | |
| rc_t | next_bytes (bool &eof) |
| Pin the next range of bytes in the record. | |
| bool | pinned () const |
| True if something currently pinned. | |
| bool | pinned_all () const |
| True if the entire record pinned. | |
| bool | up_to_date () const |
| True if record is pinned and the pin_i is valid. | |
| smsize_t | start_byte () const |
| Return the byte-offset (within the record) the of the pinned portion. | |
| smsize_t | length () const |
| Return the length of the pinned portion. | |
| smsize_t | hdr_size () const |
| Return the size of the pinned record's header. | |
| smsize_t | body_size () const |
| Return the size of the pinned record's body. | |
| bool | is_large () const |
| True if the record is too large to fit on a file page. | |
| bool | is_small () const |
| True if the record is small enough to fit on a file page. | |
| int | large_impl () const |
| The kind of large-record implementation used for the pinned record. | |
| const rid_t & | rid () const |
| Return the record ID of the pinned record. | |
| const char * | hdr () const |
| Return a pointer to the pinned record's header in the buffer pool. | |
| const char * | body () |
| Return a pointer into the pinned-record-portion in the buffer pool. | |
| rc_t | update_rec (smsize_t start, const vec_t &data, int *old_value=0) |
| Overwrite a portion of the pinned record with new data. | |
| rc_t | update_rec_hdr (smsize_t start, const vec_t &hdr) |
| Update the pinned record's header. | |
| rc_t | append_rec (const vec_t &data) |
| Append to a pinned record. | |
| rc_t | truncate_rec (smsize_t amount) |
| Shorten a record. | |
| const record_t * | rec () const |
| const char * | hdr_page_data () |
| Return a pointer to the page containing the record. | |
| lpid_t | page_containing (smsize_t offset, smsize_t &start_byte) const |
| Return the ID of the page containing the given byte of the record. | |
Pin a portion of the record starting at a given location.
| [in] | rid | ID of the record of interest |
| [in] | start | Offset of the first byte of interest. |
| [in] | lmode | Lock mode to use. Pin the page containing the first byte of interest. A record lock in the given mode is acquired (if it is not already subsumed by a coarser lock or by a higher lock mode). |
| rc_t pin_i::pin | ( | const rid_t & | rid, | |
| smsize_t | start, | |||
| lock_mode_t | lock_mode, | |||
| latch_mode_t | latch_mode | |||
| ) |
Pin a portion of the record starting at a given location.
Pin a record with the given lock mode and latch mode. See pin(rid, start, lock_mode);
| void pin_i::set_ref_bit | ( | int | value | ) |
Set the reference bit to use for the buffer frame containing the pinned body page when the page is unpinned.
| [in] | value | 0 or greater. A value of 0 is a "hate" hint indicating that the frame can be reused as soon as necessary. By default, a value of 1 is used indicating the page will be cached until at least 1 sweep of the buffer clock hand has passed. Higher values cause the page to remain cached longer. |
| rc_t pin_i::repin | ( | lock_mode_t | lmode = SH |
) |
Efficiently repin a record after is size has changed or after it has been unpinned.
| [in] | lmode | SH or EX |
| rc_t pin_i::next_bytes | ( | bool & | eof | ) |
Pin the next range of bytes in the record.
| [out] | eof | Set to true if there are no more bytes to pin. When eof is reached, the previously pinned range remains pinned. |
| bool pin_i::up_to_date | ( | ) | const [inline] |
True if record is pinned and the pin_i is valid.
The pin_i is valid if it is up-to-date with the LSN on the page. In other words, use this to verify that the page has not been updated since it was pinned by this pin_i
Definition at line 289 of file pin.h.
References pinned().
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| int pin_i::large_impl | ( | ) | const [inline] |
| const char* pin_i::hdr | ( | ) | const [inline] |
Return a pointer to the pinned record's header in the buffer pool.
Definition at line 324 of file pin.h.
References pinned().
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| const char* pin_i::body | ( | ) |
Return a pointer into the pinned-record-portion in the buffer pool.
Overwrite a portion of the pinned record with new data.
| [in] | start | The offset from the beginning of the record of the place to perform the update. |
| [in] | data | A vector containing the data to place in the record at location start. |
| [out] | old_value | deprecated The portion of the record containing the start byte need not be pinned before this is called. |
Update the pinned record's header.
| [in] | start | The offset from the beginning of the header of the place to perform the update. |
| [in] | hdr | A vector containing the data to place in the header at location start. |
Append to a pinned record.
| [in] | data | A vector containing the data to append to the record's body. The end of the record need not be pinned before this is called. |
| rc_t pin_i::truncate_rec | ( | smsize_t | amount | ) |
Shorten a record.
| [in] | amount | Number of bytes to chop off the end of the pinned record's body. The end of the record need not be pinned before this is called. |
| const char* pin_i::hdr_page_data | ( | ) |
Return a pointer to the page containing the record.
This allows you to read the entire page.
| lpid_t pin_i::page_containing | ( | smsize_t | offset, | |
| smsize_t & | start_byte | |||
| ) | const |
Return the ID of the page containing the given byte of the record.
| [in] | offset | The offset from the beginning of the record of the byte of interest |
| [out] | start_byte | The offset from the beginning of the page of the byte of interest |
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