Cache count of keys in database

Former-commit-id: 7cd266030ad82b5fddd4668d666adc95e1bed475

src/server.cpp

@@ -1646,6 +1646,62 @@ int clientsCronResizeQueryBuffer(client *c) {
     return 0;
 }
 
+SymVer parseVersion(const char *version)
+{
+    SymVer ver = {-1,-1,-1};
+    long versions[3] = {-1,-1,-1};
+    const char *start = version;
+    const char *end = nullptr;
+
+    for (int iver = 0; iver < 3; ++iver)
+    {
+        end = start;
+        while (*end != '\0' && *end != '.')
+            ++end;
+
+        if (start >= end)
+            return ver;
+
+        if (!string2l(start, end - start, versions + iver))
+            return ver;
+        if (*end != '\0')
+            start = end+1;
+        else
+            break;
+    }
+    ver.major = versions[0];
+    ver.minor = versions[1];
+    ver.build = versions[2];
+    
+    return ver;
+}
+
+VersionCompareResult compareVersion(SymVer *pver)
+{
+    SymVer symVerThis = parseVersion(KEYDB_REAL_VERSION);
+    for (int iver = 0; iver < 3; ++iver)
+    {
+        long verThis, verOther;
+        switch (iver)
+        {
+        case 0:
+            verThis = symVerThis.major; verOther = pver->major;
+            break;
+        case 1:
+            verThis = symVerThis.minor; verOther = pver->minor;
+            break;
+        case 2:
+            verThis = symVerThis.build; verOther = pver->build;
+        }
+
+        if (verThis < verOther)
+            return VersionCompareResult::NewerVersion;
+        if (verThis > verOther)
+            return VersionCompareResult::OlderVersion;
+    }
+    return VersionCompareResult::EqualVerison;
+}
+
 /* This function is used in order to track clients using the biggest amount
  * of memory in the latest few seconds. This way we can provide such information
  * in the INFO output (clients section), without having to do an O(N) scan for
@@ -5397,6 +5453,13 @@ int main(int argc, char **argv) {
 
     std::set_terminate(OnTerminate);
 
+    {
+    SymVer version;
+    version = parseVersion(KEYDB_REAL_VERSION);
+    serverAssert(version.major >= 0 && version.minor >= 0 && version.build >= 0);
+    serverAssert(compareVersion(&version) == VersionCompareResult::EqualVerison);
+    }
+
 #ifdef USE_MEMKIND
     storage_init(NULL, 0);
 #endif

src/storage/rocksdb.cpp

@@ -99,6 +99,15 @@ const IStorage *RocksDBStorageProvider::clone() const
 
 RocksDBStorageProvider::~RocksDBStorageProvider()
 {
+    if (m_spbatch != nullptr)
+        endWriteBatch();
+    
+    if (m_spdb != nullptr && m_psnapshot == nullptr)
+    {
+        insert(count_key, sizeof(count_key), &m_count, sizeof(m_count), false);
+        flush();
+    }
+
     if (m_spdb != nullptr)
     {
         if (m_psnapshot != nullptr)

src/storage/rocksdb.h

@@ -5,6 +5,9 @@
 #include <rocksdb/db.h>
 #include "../fastlock.h"
 
+static const char count_key[] = "\0__keydb__count\1";
+static const char version_key[] = "\0__keydb__version\1";
+
 class RocksDBStorageProvider : public IStorage
 {
     std::shared_ptr<rocksdb::DB> m_spdb;    // Note: This must be first so it is deleted last

src/storage/rocksdbfactory.cpp

@@ -1,4 +1,5 @@
 #include "rocksdb.h"
+#include "../version.h"
 #include <rocksdb/filter_policy.h>
 #include <rocksdb/table.h>
 #include <rocksdb/utilities/options_util.h>
@@ -14,6 +15,9 @@ public:
 
     virtual IStorage *create(int db) override;
     virtual const char *name() const override;
+
+private:
+    void setVersion(rocksdb::ColumnFamilyHandle*);
 };
 
 IStorageFactory *CreateRocksDBStorageFactory(const char *path, int dbnum)
@@ -64,9 +68,26 @@ RocksDBStorageFactory::RocksDBStorageFactory(const char *dbfile, int dbnum)
     if (!status.ok())
         throw status.ToString();
 
-    for (auto handle : handles)
-        m_vecspcols.emplace_back(handle);
     m_spdb = std::shared_ptr<rocksdb::DB>(db);
+    for (auto handle : handles)
+    {
+        std::string strVersion;
+        auto status = m_spdb->Get(rocksdb::ReadOptions(), handle, rocksdb::Slice(version_key, sizeof(version_key)), &strVersion);
+        if (!status.ok())
+        {
+            setVersion(handle);
+        }
+        else
+        {
+            SymVer ver = parseVersion(strVersion.c_str());
+            auto cmp = compareVersion(&ver);
+            if (cmp == NewerVersion)
+                throw "Cannot load FLASH database created by newer version of KeyDB";
+            if (cmp == OlderVersion)
+                setVersion(handle);
+        }
+        m_vecspcols.emplace_back(handle);
+    }   
 }
 
 RocksDBStorageFactory::~RocksDBStorageFactory()
@@ -74,14 +95,33 @@ RocksDBStorageFactory::~RocksDBStorageFactory()
     m_spdb->SyncWAL();
 }
 
+void RocksDBStorageFactory::setVersion(rocksdb::ColumnFamilyHandle *handle)
+{
+    auto status = m_spdb->Put(rocksdb::WriteOptions(), handle, rocksdb::Slice(version_key, sizeof(version_key)), rocksdb::Slice(KEYDB_REAL_VERSION, strlen(KEYDB_REAL_VERSION)+1));
+    if (!status.ok())
+        throw status.ToString();
+}
+
 IStorage *RocksDBStorageFactory::create(int db)
 {
     ++db;   // skip default col family
     std::shared_ptr<rocksdb::ColumnFamilyHandle> spcolfamily(m_vecspcols[db].release());
     size_t count = 0;
-    std::unique_ptr<rocksdb::Iterator> it = std::unique_ptr<rocksdb::Iterator>(m_spdb->NewIterator(rocksdb::ReadOptions(), spcolfamily.get()));
-    for (it->SeekToFirst(); it->Valid(); it->Next()) {
-        ++count;
+    
+    std::string value;
+    auto status = m_spdb->Get(rocksdb::ReadOptions(), spcolfamily.get(), rocksdb::Slice(count_key, sizeof(count_key)), &value);
+    if (status.ok() && value.size() == sizeof(size_t))
+    {
+        count = *reinterpret_cast<const size_t*>(value.data());
+        m_spdb->Delete(rocksdb::WriteOptions(), spcolfamily.get(), rocksdb::Slice(count_key, sizeof(count_key)));
+    }
+    else
+    {
+        printf("\tDatabase was not shutdown cleanly, recomputing metrics\n");
+        std::unique_ptr<rocksdb::Iterator> it = std::unique_ptr<rocksdb::Iterator>(m_spdb->NewIterator(rocksdb::ReadOptions(), spcolfamily.get()));
+        for (it->SeekToFirst(); it->Valid(); it->Next()) {
+            ++count;
+        }
     }
     return new RocksDBStorageProvider(m_spdb, spcolfamily, nullptr, count);
 }

src/version.h

@@ -1,3 +1,28 @@
 #define KEYDB_REAL_VERSION "0.0.0"
 extern const char *KEYDB_SET_VERSION;   // Unlike real version, this can be overriden by the config
 
+enum VersionCompareResult
+{
+    EqualVerison,
+    OlderVersion,
+    NewerVersion,
+};
+
+struct SymVer
+{
+    long major;
+    long minor;
+    long build;
+};
+
+#ifdef __cplusplus
+extern "C"
+{
+#endif
+
+struct SymVer parseVersion(const char *version);
+enum VersionCompareResult compareVersion(struct SymVer *pver);
+
+#ifdef __cplusplus
+}
+#endif