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author | John Firebaugh <john.firebaugh@gmail.com> | 2016-02-09 17:19:27 -0800 |
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committer | John Firebaugh <john.firebaugh@gmail.com> | 2016-02-10 15:40:20 -0800 |
commit | db3620c58f0c3351e26b0e3bcfd23ff414f829a1 (patch) | |
tree | e8def564e12307a997270b66a4ed46b68f5e13a4 /platform/default/sqlite3.hpp | |
parent | 591012401072e63b89071787d90bf5ae4362dca1 (diff) | |
download | qtlocation-mapboxgl-db3620c58f0c3351e26b0e3bcfd23ff414f829a1.tar.gz |
[core] Implement an eviction policy for OfflineDatabase
When inserting an cached resource, or removing a region, remove least-recently used resources and tiles, not used by offline regions, until the used database size, as calculated by multiplying the number of in-use pages by the page size, is less than the maximum cache size minus 5 times the page size.
In addition, OfflineDatabase may be configured to ignore cache puts of individual resources larger than a certain size.
This policy is similar but not identical to the former SQLiteCache policy:
* It accounts for offline, by exempting resources required by offline regions from eviction.
* It must delete from two tables (resources and tiles), rather than one. Currently the strategy is naive: evict 50 rows at a time from each table.
* It makes maximumCacheSize and maximumCacheEntrySize completely independent. The SQLiteCache implementation evicted when `usedSize > maximumCacheSize - 2 * maximumCacheEntrySize`. This evicts when `usedSize > maximumCacheSize - 5 * pageSize`.
* It uses a non-unlimited default value for maximumCacheSize: 50 MB. We should have always had a limit in place; "a cache without an eviction policy is a resource leak".
Diffstat (limited to 'platform/default/sqlite3.hpp')
-rw-r--r-- | platform/default/sqlite3.hpp | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/platform/default/sqlite3.hpp b/platform/default/sqlite3.hpp index 13e92bf07f..abe83a2d44 100644 --- a/platform/default/sqlite3.hpp +++ b/platform/default/sqlite3.hpp @@ -47,6 +47,7 @@ public: Statement prepare(const char *query); int64_t lastInsertRowid() const; + uint64_t changes() const; private: sqlite3 *db = nullptr; |