This prevents wear and tear on the flash, and it also is faster in some
cases since the read-out of flash is a cheaper operation than the erasure
of flash. Some library modules (such as the esp_wifi) write out to NVS
upon every initialization without checking first that the existing value
is the same, and this speeds up initialization of modules that make
these design choices and moves it into a centralized place.
The comparison functions are based on the read-out functions of the same
name, and changes out the memcpy(...) operations for memcmp(...)
operations.
Signed-off-by: Tim Nordell <tim.nordell@nimbelink.com>
This change adds a check for compatibility between the nvs version
found on nvs flash and the one assumed by running code during nvs
initialization. Any mismatch is reported to the user using new error
code ESP_ERR_NVS_NEW_VERSION_FOUND.
This change removes the earlier limitation of 1984 bytes for storing data-blobs.
Blobs larger than the sector size are split and stored on multiple sectors.
For this purpose, two new datatypes (multi-page index and multi-page data) are
added for entries stored in the sectors. The underlying read, write, erase and find
operations are modified to support these large blobs. The change is transparent
to users of the library and no special APIs need to be used to store these large
blobs.
Currently when page is being freed, items are individually moved from
FREEING page to ACTIVE page and erased. If power-off happens during the
process, the remaining entries are moved to ACTIVE page during recovery.
The problem with this approach is there may not be enough space on
ACTIVE page for all items if an item was partially written before
power-off and erased during recovery. This change moves all the items
from FREEING to ACTIVE page and then erased the FREEING page, If
power-off happens during the process, then ACTIVE page is erased and the
process is restarted.
Users needs functions to count the number of free and used entries.
1. `nvs_get_stats()` This function return structure of statistic about the uspace NVS.
(Struct: used_entries, free_entries, total_entries and namespace_count)
2. `nvs_get_used_entry_count()` The second function return amount of entries in the namespace (by handler)
3. Added unit tests.
Closes TW<12282>
Writing values longer than half of the page size (with header taken into
account) causes fragmentation issues. Previously it was suggested on the
forum that using long values may cause issues, but this wasn’t checked
in the library itself, and wasn’t documented. This change adds necessary
checks and introduces the new error code.
Documentation is also fixed to reflect the fact that the maximum length
of the key is 15 characters, not 16.
Since read cache was introduced at page level, search cache became
useless in terms of reducing the number of flash read operations.
In addition to that, search cache used an assumption that if pointers to
keys are identical, the keys are also identical, which was proven wrong
by applications which generate key names dynamically.
This change removes CachedFindInfo, and all its uses. This is done at
expense of a small extra number of CPU operations (looking up a value in
the read cache is slightly more expensive) but no extra flash read
operations.
Ref TW12505
Ref https://github.com/espressif/arduino-esp32/issues/365
Introduces new internal function, Page::alterEntryRangeState, which gathers changes to multiple elements of entry state table into a single write, provided that these changes fall into a single word. This allows changing state of up to 16 entries in a single write.
Also adds new function, writeEntryData, which writes the whole payload of SZ and BLOB type entries in one go, instead of splitting it into multiple 32-byte writes.
This reduces number of writes required for SZ and BLOB entries.
This commit fixes several issues with state handling in nvs::Page. It also adds extra consistency checks in nvs::PageManger initialization.
These changes were verified with a new long-running test ("test recovery from sudden poweroff"). This test works by repeatedly performing same pseudorandom sequence of calls to nvs_ APIs. Each time it repeats the sequence, it introduces a failure into one of flash operations (write or erase). So if one iteration of this test needs, say, 25000 flash operations, then this test will run 25000 iterations, each time introducing the failure point at different location.
