feat: promql create and skeleton (#720)

* feat: adds promql crate

* feat: adds promql-parser dependency and rfc doc

* fix: dependencies order in servers crate

* fix: forgot error.rs

* fix: comment

* fix: license header

* fix: remove docs/rfc/20221207_promql.md

src/promql/Cargo.toml

@@ -0,0 +1,9 @@
+[package]
+name = "promql"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+common-error = { path = "../common/error" }
+promql-parser = { git = "https://github.com/GreptimeTeam/promql-parser.git", rev = "71d8a90" }
+snafu = { version = "0.7", features = ["backtraces"] }

src/promql/src/engine.rs

@@ -0,0 +1,36 @@
+// Copyright 2022 Greptime Team
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+use std::sync::Arc;
+
+use promql_parser::parser::Value;
+
+use crate::error::Result;
+
+mod evaluator;
+mod functions;
+
+pub use evaluator::*;
+
+pub struct Context {}
+
+pub struct Query {}
+
+pub struct Engine {}
+
+impl Engine {
+    pub fn exec(_ctx: &Context, _q: Query) -> Result<Arc<dyn Value>> {
+        unimplemented!();
+    }
+}

src/promql/src/engine/evaluator.rs

@@ -0,0 +1,29 @@
+// Copyright 2022 Greptime Team
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+use std::sync::Arc;
+
+use promql_parser::parser::{Expr, Value};
+
+use crate::engine::Context;
+use crate::error::Result;
+
+/// An evaluator evaluates given expressions over given fixed timestamps.
+pub struct Evaluator {}
+
+impl Evaluator {
+    pub fn eval(_ctx: &Context, _expr: &Expr) -> Result<Arc<dyn Value>> {
+        unimplemented!();
+    }
+}

src/promql/src/engine/functions.rs

@@ -0,0 +1,15 @@
+// Copyright 2022 Greptime Team
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//! PromQL functions

src/promql/src/error.rs

@@ -0,0 +1,50 @@
+// Copyright 2022 Greptime Team
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+use std::any::Any;
+
+use common_error::prelude::*;
+
+common_error::define_opaque_error!(Error);
+
+#[derive(Debug, Snafu)]
+#[snafu(visibility(pub))]
+pub enum InnerError {
+    #[snafu(display("Unsupported expr type: {}", name))]
+    UnsupportedExpr { name: String, backtrace: Backtrace },
+}
+
+impl ErrorExt for InnerError {
+    fn status_code(&self) -> StatusCode {
+        use InnerError::*;
+        match self {
+            UnsupportedExpr { .. } => StatusCode::InvalidArguments,
+        }
+    }
+    fn backtrace_opt(&self) -> Option<&Backtrace> {
+        ErrorCompat::backtrace(self)
+    }
+
+    fn as_any(&self) -> &dyn Any {
+        self
+    }
+}
+
+impl From<InnerError> for Error {
+    fn from(e: InnerError) -> Error {
+        Error::new(e)
+    }
+}
+
+pub type Result<T> = std::result::Result<T, Error>;

src/promql/src/lib.rs

@@ -0,0 +1,16 @@
+// Copyright 2022 Greptime Team
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+pub mod engine;
+pub mod error;

src/servers/Cargo.toml

@@ -40,12 +40,12 @@ regex = "1.6"
 rustls = "0.20"
 rustls-pemfile = "1.0"
 schemars = "0.8"
-strum = { version = "0.24", features = ["derive"] }
 serde = "1.0"
 serde_json = "1.0"
 session = { path = "../session" }
 snafu = { version = "0.7", features = ["backtraces"] }
 snap = "1"
+strum = { version = "0.24", features = ["derive"] }
 table = { path = "../table" }
 tokio = { version = "1.20", features = ["full"] }
 tokio-rustls = "0.23"