rust-workshop => backend-rust

backend-rust/step2-database-only/Cargo.toml

@@ -0,0 +1,24 @@
+[package]
+name = "fluid"
+version = "0.1.0"
+authors = ["Fluence Labs"]
+publish = false
+description = "Decentralized feed built on Fluence"
+edition = "2018"
+
+[lib]
+name = "fluid"
+path = "src/lib.rs"
+crate-type = ["cdylib"]
+
+[profile.release]
+debug = false
+lto = true
+opt-level = "z"
+panic = "abort"
+
+[dependencies]
+serde = { version = "=1.0.88", features = ["derive"] }
+serde_json = { version = "=1.0.38", features = ["raw_value"] }
+log = "0.4"
+fluence = { version = "0.1.6", features = ["wasm_logger"] }

backend-rust/step2-database-only/src/database.rs

@@ -0,0 +1,63 @@
+use log;
+
+use crate::api::AppResult;
+use crate::errors::err_msg;
+use crate::ffi;
+
+// Execute query on SQLite
+pub fn query(query: String) -> AppResult<String> {
+    log::debug!("executing query: '{}'", query);
+
+    unsafe {
+        // Convert query string to bytes
+        let query_bytes = query.as_bytes();
+        // Allocate memory for query in SQLite module
+        let query_ptr = ffi::allocate(query_bytes.len());
+
+        // Store query in SQLite's memory
+        for (i, byte) in query_bytes.iter().enumerate() {
+            let ptr = query_ptr + i as i32;
+            ffi::store(ptr, *byte);
+        }
+
+        // Execute the query, and get pointer to the result
+        let result_ptr = ffi::invoke(query_ptr, query_bytes.len());
+
+        // First 4 bytes at result_ptr location encode result size, read that first
+        let mut result_size: usize = 0;
+        for i in 0..3 {
+            let ptr = result_ptr + i as i32;
+            let b = ffi::load(ptr) as usize;
+            result_size = result_size + (b << (8 * i));
+        }
+        // Now we know exact size of the query execution result
+
+        // Read query execution result byte-by-byte
+        let mut result_bytes = vec![0; result_size as usize];
+        for i in 4..(result_size + 4) {
+            let ptr = result_ptr + i as i32;
+            let b = ffi::load(ptr);
+            result_bytes[i as usize - 4] = b;
+        }
+
+        // Deallocate query result
+        ffi::deallocate(result_ptr, result_size + 4);
+
+        // Decode query result to a utf8 string
+        let result_str = std::str::from_utf8(result_bytes.as_slice());
+
+        // Log if there's an error
+        if result_str.is_err() {
+            log::error!("unable to decode result from bytes: {:#x?}", result_bytes);
+        }
+        // Wrap error with a better message, and return Result
+        result_str
+            .map_err(|e| {
+                err_msg(&format!(
+                    "unable to decode result from bytes {:#x?}: {}",
+                    result_bytes, e
+                ))
+            })
+            .map(|s| s.to_string())
+    }
+}

backend-rust/step2-database-only/src/errors.rs

@@ -0,0 +1,16 @@
+use std::fmt;
+
+#[derive(Debug)]
+pub struct Error(String);
+
+impl std::error::Error for Error {}
+
+impl fmt::Display for Error {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "{}", self.0)
+    }
+}
+
+pub fn err_msg(s: &str) -> Box<Error> {
+    Error(s.to_string()).into()
+}

backend-rust/step2-database-only/src/ffi.rs

@@ -0,0 +1,26 @@
+// Description of inter-module communication
+//
+// Allows fluid module to call methods from sqlite module
+
+#[link(wasm_import_module = "sqlite")]
+extern "C" {
+    // Allocate chunk of SQLite memory, and return a pointer to that memory
+    #[link_name = "sqlite_allocate"]
+    pub fn allocate(size: usize) -> i32;
+
+    // Deallocate chunk of memory after it's not used anymore
+    #[link_name = "sqlite_deallocate"]
+    pub fn deallocate(ptr: i32, size: usize);
+
+    // Put 1 byte at ptr location in SQLite memory
+    #[link_name = "sqlite_store"]
+    pub fn store(ptr: i32, byte: u8);
+
+    // Read 1 byte from ptr location of SQLite memory
+    #[link_name = "sqlite_load"]
+    pub fn load(ptr: i32) -> u8;
+
+    // Call SQLite's invocation handler with data specified by pointer and size
+    #[link_name = "sqlite_invoke"]
+    pub fn invoke(ptr: i32, size: usize) -> i32;
+}

backend-rust/step2-database-only/src/lib.rs

@@ -0,0 +1,40 @@
+use fluence::sdk::*;
+use serde_json::value::RawValue;
+
+use api::Request;
+use api::Response;
+
+use crate::api::AppResult;
+use crate::errors::err_msg;
+
+pub mod database;
+pub mod errors;
+pub mod ffi;
+
+fn init() {
+    logger::WasmLogger::init_with_level(log::Level::Info).unwrap();
+}
+
+#[invocation_handler(init_fn = init)]
+fn run(nickname: String) -> String {
+    // Create table for messages storage
+    database::query("CREATE TABLE messages(msg text, username text)".to_string());
+
+    // Insert message 'Hello, username!' using `nickname` as author's username
+    database::query(format!(
+        r#"INSERT INTO messages VALUES("{}","{}")"#,
+        "Hello, username!", nickname
+    ));
+
+    // Get all messages
+    let messages = database::query("SELECT * FROM messages".to_string());
+    log::info!("messages: {}", messages);
+
+    // Get all messages as JSON via SQLite's JSON extension
+    database::query(
+        "SELECT json_group_array(
+            json_object('msg', msg, 'username', username)
+        ) AS json_result FROM (SELECT * FROM messages)"
+            .to_string(),
+    )
+}