add Setex() Psetex() and Strlen() (OpenAtomFoundation#2)

* add Setex() Psetex() and Strlen()

* add Setnx() and Append() (OpenAtomFoundation#1)

* add examples

* add Setnx() and Append()

* bugfix add the lock before Put()

* bugfix logic errors“

* remove Psetex()

* fix confict

* fix conflict

* remove Psetex() example

* assert ttl argument greater than zero

examples/strings_example.cc

@@ -49,5 +49,16 @@ int main() {
   s = db.Compact();
   printf("Compact return: %s\n", s.ToString().c_str());
 
+  s = db.Setex("TEST_KEY", "TEST_VALUE", 1);
+  printf("Setex return: %s\n", s.ToString().c_str());
+  std::this_thread::sleep_for(std::chrono::milliseconds(2000));
+  s = db.Get("TEST_KEY", &value);
+  printf("Get return: %s, value: %s\n", s.ToString().c_str(), value.c_str());
+
+  s = db.Set("TEST_KEY", "TEST_VALUE");
+  int32_t len = 0;
+  s = db.Strlen("TEST_KEY", &len);
+  printf("Strlen return: %s, strlen: %d\n", s.ToString().c_str(), len);
+
   return 0;
 }

include/blackwidow/blackwidow.h

@@ -33,6 +33,8 @@ class BlackWidow {
   Status Get(const Slice& key, std::string* value);
   Status Setnx(const Slice& key, const Slice& value, int32_t* ret);
   Status Append(const Slice& key, const Slice& value, int32_t* ret);
+  Status Setex(const Slice& key, const Slice& value, int32_t ttl);
+  Status Strlen(const Slice& key, int32_t* len);
 
   // Keys Commands
   Status Expire(const Slice& key, int32_t ttl);

src/blackwidow.cc

@@ -57,4 +57,12 @@ Status BlackWidow::Expire(const Slice& key, int32_t ttl) {
   return strings_db_->Expire(key, ttl);
 }
 
+Status BlackWidow::Setex(const Slice& key, const Slice& value, int32_t ttl) {
+  return strings_db_->Setex(key, value, ttl);
+}
+
+Status BlackWidow::Strlen(const Slice& key, int32_t* len) {
+  return strings_db_->Strlen(key, len);
+}
+
 }  //  namespace blackwidow

src/redis_strings.cc

@@ -114,4 +114,24 @@ Status RedisStrings::CompactRange(const rocksdb::Slice* begin,
   return db_->CompactRange(default_compact_range_options_, begin, end);
 }
 
+Status RedisStrings::Setex(const Slice& key, const Slice& value, int32_t ttl) {
+  //the ttl argument must greater than zero, to be compatible with redis
+  assert(ttl > 0);
+  InternalStringsValue internal_value(value);
+  internal_value.SetRelativeTimestamp(ttl);
+  ScopeRecordLock l(lock_mgr_, key);
+  return db_->Put(default_write_options_, key, internal_value.Encode());
+}
+
+Status RedisStrings::Strlen(const Slice& key, int32_t *len) {
+  std::string value;
+  Status s = Get(key, &value);
+  if (s.ok()) {
+    *len = value.size();
+  } else {
+    *len = 0;
+  }
+  return s;
+}
+
 }  //  namespace blackwidow

src/redis_strings.h

@@ -23,6 +23,8 @@ class RedisStrings : public Redis {
   Status Get(const Slice& key, std::string* value);
   Status Setnx(const Slice& key, const Slice& value, int32_t* ret);
   Status Append(const Slice& key, const Slice& value, int32_t* ret);
+  Status Setex(const Slice& key, const Slice& value, int32_t ttl);
+  Status Strlen(const Slice& key, int32_t *len);
 
   // Common Commands
   virtual Status Open(const rocksdb::Options& options,