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use ForEachOverlapping to impl Get

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This commit is contained in:
neal-zhu 2019-06-11 19:16:49 +08:00
parent 4cb80b7ddc
commit 6a90bb91ee
1 changed files with 45 additions and 70 deletions
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115
db/version_set.cc
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@ -330,94 +330,69 @@ Status Version::Get(const ReadOptions& options, const LookupKey& k,
const Comparator* ucmp = vset_->icmp_.user_comparator();
Status s;
stats->seek_file = nullptr;
stats->seek_file_level = -1;
FileMetaData* last_file_read = nullptr;
int last_file_read_level = -1;
struct State {
GetStats* stats;
const ReadOptions* options;
Slice ikey;
Slice user_key;
const Comparator* ucmp;
std::string* value;
// We can search level-by-level since entries never hop across
// levels. Therefore we are guaranteed that if we find data
// in a smaller level, later levels are irrelevant.
std::vector<FileMetaData*> tmp;
FileMetaData* tmp2;
for (int level = 0; level < config::kNumLevels; level++) {
size_t num_files = files_[level].size();
if (num_files == 0) continue;
VersionSet *vset;
Status s;
// Get the list of files to search in this level
FileMetaData* const* files = &files_[level][0];
if (level == 0) {
// Level-0 files may overlap each other. Find all files that
// overlap user_key and process them in order from newest to oldest.
tmp.reserve(num_files);
for (uint32_t i = 0; i < num_files; i++) {
FileMetaData* f = files[i];
if (ucmp->Compare(user_key, f->smallest.user_key()) >= 0 &&
ucmp->Compare(user_key, f->largest.user_key()) <= 0) {
tmp.push_back(f);
}
}
if (tmp.empty()) continue;
static bool Match(void* arg, int level, FileMetaData* f) {
State* state = reinterpret_cast<State*>(arg);
std::sort(tmp.begin(), tmp.end(), NewestFirst);
files = &tmp[0];
num_files = tmp.size();
} else {
// Binary search to find earliest index whose largest key >= ikey.
uint32_t index = FindFile(vset_->icmp_, files_[level], ikey);
if (index >= num_files) {
files = nullptr;
num_files = 0;
} else {
tmp2 = files[index];
if (ucmp->Compare(user_key, tmp2->smallest.user_key()) < 0) {
// All of "tmp2" is past any data for user_key
files = nullptr;
num_files = 0;
} else {
files = &tmp2;
num_files = 1;
}
}
}
for (uint32_t i = 0; i < num_files; ++i) {
if (last_file_read != nullptr && stats->seek_file == nullptr) {
if (state->stats->seek_file == nullptr) {
// We have had more than one seek for this read. Charge the 1st file.
stats->seek_file = last_file_read;
stats->seek_file_level = last_file_read_level;
state->stats->seek_file = f;
state->stats->seek_file_level = level;
}
FileMetaData* f = files[i];
last_file_read = f;
last_file_read_level = level;
Saver saver;
saver.state = kNotFound;
saver.ucmp = ucmp;
saver.user_key = user_key;
saver.value = value;
s = vset_->table_cache_->Get(options, f->number, f->file_size, ikey,
&saver, SaveValue);
saver.ucmp = state->ucmp;
saver.user_key = state->user_key;
saver.value = state->value;
Status s = state->vset->table_cache_->Get(*state->options, f->number,
f->file_size, state->ikey,
&saver, SaveValue);
if (!s.ok()) {
return s;
state->s = s;
return false;
}
switch (saver.state) {
case kNotFound:
break; // Keep searching in other files
return true; // Keep saerching in other files
case kFound:
return s;
state->s = s;
return false;
case kDeleted:
s = Status::NotFound(Slice()); // Use empty error message for speed
return s;
return false;
case kCorrupt:
s = Status::Corruption("corrupted key for ", user_key);
return s;
state->s = Status::Corruption("corrupted key for ", state->user_key);
return false;
}
}
}
};
return Status::NotFound(Slice()); // Use an empty error message for speed
stats->seek_file = nullptr;
stats->seek_file_level = -1;
State state;
state.s = Status::NotFound(Slice());
state.stats = stats;
state.ikey = ikey;
state.user_key = user_key;
state.ucmp = ucmp;
state.value = value;
state.vset = vset_;
ForEachOverlapping(user_key, ikey, &state, &State::Match);
return state.s;
}
bool Version::UpdateStats(const GetStats& stats) {