feat scylla: LWT transactions, sample service and docs

Author: gearonixx

samples/scylla_service/CMakeLists.txt

@@ -4,5 +4,7 @@ project(userver-samples-scylla_service CXX)
 find_package(userver COMPONENTS scylla REQUIRED)
 userver_setup_environment()
 
-add_executable(${PROJECT_NAME} main.cpp)
+add_executable(${PROJECT_NAME} src/main.cpp src/helpers.cpp)
 target_link_libraries(${PROJECT_NAME} userver::scylla)
+
+userver_testsuite_add_simple()

samples/scylla_service/README.md

@@ -0,0 +1,157 @@
+# scylla_service demo
+
+Enter the ScyllaDB container and open cqlsh
+
+```shell
+docker exec -it scylla cqlsh
+```
+
+Create the keyspace and table
+
+```sql
+CREATE KEYSPACE IF NOT EXISTS examples
+    WITH REPLICATION = { 'class' : 'SimpleStrategy', 'replication_factor' : 1 };
+
+CREATE TABLE IF NOT EXISTS examples.basic (
+    key text PRIMARY KEY,
+    bln boolean,
+    flt float,
+    dbl double,
+    i32 int,
+    i64 bigint
+);
+```
+
+
+---
+
+```shell
+docker exec -it scylla-dev-1 bash
+```
+
+## Operations
+
+
+### InsertOne
+
+```bash
+curl -sS -X POST "http://localhost:8080/v1/kv" \
+    -H 'Content-Type: application/json' \
+    -d '{"key":"alpha","bln":true,"i32":1,"i64":42,"flt":1.5,"dbl":2.5}'
+```
+
+### 2. SelectOne
+
+```bash
+curl -sS "http://localhost:8080/v1/kv?key=alpha"
+
+# should return 404
+curl -sS -w '\n%{http_code}\n' "http://localhost:8080/v1/kv?key=does-not-exist"
+```
+
+### 3. UpdateOne
+
+```bash
+curl -sS -X PATCH "http://localhost:8080/v1/kv?key=alpha" \
+    -H 'Content-Type: application/json' \
+    -d '{"bln":false,"i32":99}'
+
+curl -sS "http://localhost:8080/v1/kv?key=alpha"
+```
+
+### 4. DeleteOne
+
+```bash
+curl -sS -X DELETE "http://localhost:8080/v1/kv?key=alpha"
+```
+
+### 5. InsertMany
+
+```bash
+curl -sS -X POST "http://localhost:8080/v1/kv/bulk" \
+    -H 'Content-Type: application/json' \
+    -d '[
+          {"key":"bulk-1","i32":1,"bln":true},
+          {"key":"bulk-2","i32":2,"bln":true},
+          {"key":"bulk-3","i32":3,"bln":false}
+        ]'
+```
+
+### 6. SelectMany
+
+```bash
+curl -sS "http://localhost:8080/v1/kv/list"
+
+curl -sS "http://localhost:8080/v1/kv/list?limit=2"
+```
+
+### 7. Count
+
+```bash
+curl -sS "http://localhost:8080/v1/kv/count"
+
+curl -sS "http://localhost:8080/v1/kv/count?key=bulk-1"
+```
+
+### 8. Truncate
+
+```bash
+curl -sS -X POST "http://localhost:8080/v1/kv/truncate"
+
+curl -sS "http://localhost:8080/v1/kv/count"
+```
+
+### 9. InsertOne IF NOT EXISTS (LWT)
+
+```bash
+curl -sS -X POST "http://localhost:8080/v1/kv/create_if_absent" \
+    -H 'Content-Type: application/json' \
+    -d '{"key":"lwt-1","i32":100}'
+
+curl -sS -w '\n%{http_code}\n' -X POST "http://localhost:8080/v1/kv/create_if_absent" \
+    -H 'Content-Type: application/json' \
+    -d '{"key":"lwt-1","i32":999}'
+```
+
+### 10. UpdateOne IF col = ? (Compare-And-Set)
+
+```bash
+curl -sS -X POST "http://localhost:8080/v1/kv/cas?key=lwt-1" \
+    -H 'Content-Type: application/json' \
+    -d '{"expect":{"i32":100},"set":{"i32":101}}'
+
+curl -sS -w '\n%{http_code}\n' -X POST "http://localhost:8080/v1/kv/cas?key=lwt-1" \
+    -H 'Content-Type: application/json' \
+    -d '{"expect":{"i32":100},"set":{"i32":200}}'
+```
+
+### 11. DeleteOne IF EXISTS
+
+```bash
+curl -sS -X DELETE "http://localhost:8080/v1/kv/delete_if_exists?key=lwt-1"
+
+curl -sS -w '\n%{http_code}\n' -X DELETE "http://localhost:8080/v1/kv/delete_if_exists?key=lwt-1"
+```
+
+
+---
+
+Current `static_config.yaml`
+
+```yaml
+scylla-db:
+    dbconnection: scylla
+    consistency: local_quorum
+    serial_consistency: local_serial
+    request_timeout: 10s
+    pool_size: 16
+    app_name: scylla_sample
+    shard_awareness: true
+    retry_policy: default
+    load_balancing_policy: round_robin
+    speculative_execution:
+        enabled: false
+        max_attempts: 2
+        delay: 100ms
+    default_keyspace: examples
+```

samples/scylla_service/main.cpp

@@ -0,0 +1,7 @@
+{
+    "scylla_settings": {
+        "scylla_example": {
+            "hosts": "scylla"
+        }
+    }
+}