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

* add examples

* add Setnx() and Append()

* bugfix add the lock before Put()

* bugfix logic errors“

.gitignore

@@ -34,3 +34,5 @@
 # Others
 tags
 src/build_version.cc
+examples/strings_example
+examples/db

examples/strings_example.cc

@@ -18,16 +18,34 @@ int main() {
     printf("Open failed, error: %s\n", s.ToString().c_str());
     return -1;
   }
+  // Set
   s = db.Set("TEST_KEY", "TEST_VALUE");
   printf("Set return: %s\n", s.ToString().c_str());
+
+  // Get
   std::string value;
   s = db.Get("TEST_KEY", &value);
   printf("Get return: %s, value: %s\n", s.ToString().c_str(), value.c_str());
+
+  // Setnx
+  int32_t ret;
+  s = db.Setnx("TEST_KEY", "TEST_VALUE", &ret);
+  printf("Setnx return: %s, value: %s, ret: %d\n", s.ToString().c_str(), value.c_str(), ret);
+
+  // Append
+  std::string append_value;
+  s = db.Append("TEST_KEY", "APPEND_VALUE", &ret);
+  s = db.Get("TEST_KEY", &append_value);
+  printf("Append return: %s, value: %s, ret: %d\n", s.ToString().c_str(), append_value.c_str(), ret);
+
+  // Expire
   s = db.Expire("TEST_KEY", 1);
   printf("Expire return: %s\n", s.ToString().c_str());
   std::this_thread::sleep_for(std::chrono::milliseconds(2500));
   s = db.Get("TEST_KEY", &value);
   printf("Get return: %s, value: %s\n", s.ToString().c_str(), value.c_str());
+
+  // Compact
   s = db.Compact();
   printf("Compact return: %s\n", s.ToString().c_str());
 

include/blackwidow/blackwidow.h

@@ -31,6 +31,8 @@ class BlackWidow {
   // Strings Commands
   Status Set(const Slice& key, const Slice& value);
   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);
 
   // Keys Commands
   Status Expire(const Slice& key, int32_t ttl);

src/blackwidow.cc

@@ -45,6 +45,14 @@ Status BlackWidow::Get(const Slice& key, std::string* value) {
   return strings_db_->Get(key, value);
 }
 
+Status BlackWidow::Setnx(const Slice& key, const Slice& value, int32_t* ret) {
+  return strings_db_->Setnx(key, value, ret);
+}
+
+Status BlackWidow::Append(const Slice& key, const Slice& value, int32_t* ret) {
+  return strings_db_->Append(key, value, ret);
+}
+
 Status BlackWidow::Expire(const Slice& key, int32_t ttl) {
   return strings_db_->Expire(key, ttl);
 }

src/redis_strings.cc

@@ -39,6 +39,56 @@ Status RedisStrings::Get(const Slice& key, std::string* value) {
   return s;
 }
 
+Status RedisStrings::Setnx(const Slice& key, const Slice& value, int32_t* ret) {
+  *ret = 0;
+  std::string old_value;
+  ScopeRecordLock l(lock_mgr_, key);
+  Status s = db_->Get(default_read_options_, key, &old_value);
+  if (s.ok()) {
+    ParsedInternalStringsValue internal_value(&old_value);
+    if (internal_value.IsStale()) {
+      InternalStringsValue new_value(value);
+      s = db_->Put(default_write_options_, key, new_value.Encode());
+      if (s.ok()) {
+        *ret = 1;
+      }
+    }
+  } else if (s.IsNotFound()) {
+    InternalStringsValue new_value(value);
+    s = db_->Put(default_write_options_, key, new_value.Encode());
+    if (s.ok()) {
+      *ret = 1;
+    }
+  }
+  return s;
+}
+
+Status RedisStrings::Append(const Slice& key, const Slice& value, int32_t* ret) {
+  std::string old_value;
+  *ret = 0;
+  ScopeRecordLock l(lock_mgr_, key);
+  Status s = db_->Get(default_read_options_, key, &old_value);
+  if (s.ok()) {
+    ParsedInternalStringsValue internal_value(&old_value);
+    if (internal_value.IsStale()) {
+      *ret = value.size();
+      InternalStringsValue new_value(value);
+      return db_->Put(default_write_options_, key, new_value.Encode());
+    } else {
+      internal_value.StripSuffix();
+      *ret = old_value.size() + value.size();
+      old_value += value.data();
+      InternalStringsValue new_value(old_value);
+      return db_->Put(default_write_options_, key, new_value.Encode());
+    }
+  } else if (s.IsNotFound()) {
+    *ret = value.size();
+    InternalStringsValue internal_value(value);
+    return db_->Put(default_write_options_, key, internal_value.Encode());
+  }
+  return s;
+}
+
 Status RedisStrings::Expire(const Slice& key, int32_t ttl) {
   std::string value;
   ScopeRecordLock l(lock_mgr_, key);

src/redis_strings.h

@@ -21,6 +21,8 @@ class RedisStrings : public Redis {
   // Strings Commands
   Status Set(const Slice& key, const Slice& value);
   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);
 
   // Common Commands
   virtual Status Open(const rocksdb::Options& options,