LevelDB 源码分析

Posted on Edited on Disqus:

Condition Variable与Mutex的比较
Mutexes are low-level primitives used to coordinate concurrent access to mutable data.If one thread has locked a mutex, then another thread attempting to lock that same mutex will wait until the first thread is done
https://en.cppreference.com/w/cpp/thread/condition_variable

reinterpret_cast

Features-Not-in-LevelDB

SSTable and Log Structured Storage: LevelDB

dbformat.h
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//A helper class useful for DBImpl::Get()
class LookupKey {
...
private:
    const char *start_;     //user key length varint32 
    const char *kstart_;    //user key  char[klength]
    const char *end_;       //sequence number + value type uint64
    char space_[200];       //Avoid allocation for short keys
}
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struct FileMetaData {
    int refs;                   
    int allowed_seeks;          // Seeks allowed until compaction
    uint64_t number;
    uint64_t file_size;         // File size in bytes
    InternalKey smallest;       // Smallest internal key served by table
    InternalKey largest;        // Largest internal key served by table

    FileMetaData() : refs(0), allowed_seeks(1 << 30), file_size(0) {}
};