Minor HTTP refactor

src/api/lib.zig

@@ -94,15 +94,15 @@ pub fn setupAdmin(db: sql.Db, origin: []const u8, username: []const u8, password
 }
 
 pub const ApiSource = struct {
-    db_conn: *sql.Conn,
+    db_conn_pool: *sql.ConnPool,
 
     pub const Conn = ApiConn(sql.Db);
 
     const root_username = "root";
 
-    pub fn init(db_conn: *sql.Conn) !ApiSource {
+    pub fn init(pool: *sql.ConnPool) !ApiSource {
         return ApiSource{
-            .db_conn = db_conn,
+            .db_conn_pool = pool,
         };
     }
 
@@ -110,7 +110,7 @@ pub const ApiSource = struct {
         var arena = std.heap.ArenaAllocator.init(alloc);
         errdefer arena.deinit();
 
-        const db = try self.db_conn.acquire();
+        const db = try self.db_conn_pool.acquire();
         const community = try services.communities.getByHost(db, host, arena.allocator());
 
         return Conn{
@@ -125,7 +125,7 @@ pub const ApiSource = struct {
         var arena = std.heap.ArenaAllocator.init(alloc);
         errdefer arena.deinit();
 
-        const db = try self.db_conn.acquire();
+        const db = try self.db_conn_pool.acquire();
         const community = try services.communities.getByHost(db, host, arena.allocator());
 
         const token_info = try services.auth.verifyToken(
@@ -157,6 +157,7 @@ fn ApiConn(comptime DbConn: type) type {
 
         pub fn close(self: *Self) void {
             self.arena.deinit();
+            self.db.releaseConnection();
         }
 
         fn isAdmin(self: *Self) bool {

src/http/lib.zig

@@ -3,13 +3,15 @@ const ciutf8 = @import("util").ciutf8;
 
 const request = @import("./request.zig");
 
-pub const server = @import("./server.zig");
+const server = @import("./server.zig");
 
 pub const Method = std.http.Method;
 pub const Status = std.http.Status;
 
 pub const Request = request.Request;
-pub const Server = server.Server;
+pub const serveConn = server.serveConn;
+pub const Response = server.Response;
+pub const Handler = server.Handler;
 
 pub const Headers = std.HashMap([]const u8, []const u8, struct {
     pub fn eql(_: @This(), a: []const u8, b: []const u8) bool {

src/http/request.zig

@@ -4,13 +4,25 @@ const http = @import("./lib.zig");
 const parser = @import("./request/parser.zig");
 
 pub const Request = struct {
+    pub const Protocol = enum {
+        http_1_0,
+        http_1_1,
+    };
+
+    protocol: Protocol,
+    source_address: ?std.net.Address,
+
     method: http.Method,
-    path: []const u8,
+    uri: []const u8,
     headers: http.Headers,
     body: ?[]const u8 = null,
 
-    pub fn parse(alloc: std.mem.Allocator, reader: anytype) !Request {
-        return parser.parse(alloc, reader);
+    pub fn parse(alloc: std.mem.Allocator, reader: anytype, addr: std.net.Address) !Request {
+        return parser.parse(alloc, reader, addr);
+    }
+
+    pub fn parseFree(self: Request, alloc: std.mem.Allocator) void {
+        parser.parseFree(alloc, self);
     }
 };
 

src/http/request/parser.zig

@@ -22,34 +22,45 @@ const Encoding = enum {
     chunked,
 };
 
-pub fn parse(alloc: std.mem.Allocator, reader: anytype) !Request {
-    var request: Request = undefined;
-
-    try parseLine(alloc, &request, reader);
-    request.headers = try parseHeaders(alloc, reader);
-
-    if (request.method.requestHasBody()) {
-        request.body = try readBody(alloc, request.headers, reader);
-    } else {
-        request.body = null;
-    }
-
-    return request;
-}
-
-fn parseLine(alloc: std.mem.Allocator, request: *Request, reader: anytype) !void {
-    request.method = try parseMethod(reader);
-    request.path = reader.readUntilDelimiterAlloc(alloc, ' ', max_path_len) catch |err| switch (err) {
+pub fn parse(alloc: std.mem.Allocator, reader: anytype, address: std.net.Address) !Request {
+    const method = try parseMethod(reader);
+    const uri = reader.readUntilDelimiterAlloc(alloc, ' ', max_path_len) catch |err| switch (err) {
         error.StreamTooLong => return error.RequestUriTooLong,
         else => return err,
     };
-    errdefer alloc.free(request.path);
+    errdefer alloc.free(uri);
 
-    try checkProto(reader);
+    const proto = try parseProto(reader);
 
     // discard \r\n
     _ = try reader.readByte();
     _ = try reader.readByte();
+
+    var headers = try parseHeaders(alloc, reader);
+    errdefer freeHeaders(alloc, &headers);
+
+    const body = if (method.requestHasBody())
+        try readBody(alloc, headers, reader)
+    else
+        null;
+    errdefer if (body) |b| alloc.free(b);
+
+    const eff_addr = if (headers.get("X-Real-IP")) |ip|
+        std.net.Address.parseIp(ip, address.getPort()) catch {
+            return error.BadRequest;
+        }
+    else
+        address;
+
+    return Request{
+        .protocol = proto,
+        .source_address = eff_addr,
+
+        .method = method,
+        .uri = uri,
+        .headers = headers,
+        .body = body,
+    };
 }
 
 fn parseMethod(reader: anytype) !Method {
@@ -68,7 +79,7 @@ fn parseMethod(reader: anytype) !Method {
     return error.MethodNotImplemented;
 }
 
-fn checkProto(reader: anytype) !void {
+fn parseProto(reader: anytype) !Request.Protocol {
     var buf: [8]u8 = undefined;
     const proto = reader.readUntilDelimiter(&buf, '/') catch |err| switch (err) {
         error.StreamTooLong => return error.UnknownProtocol,
@@ -84,14 +95,24 @@ fn checkProto(reader: anytype) !void {
         return error.BadRequest;
     }
 
-    if (buf[0] != '1' or buf[2] != '1') {
-        return error.HttpVersionNotSupported;
-    }
+    if (buf[0] != '1') return error.HttpVersionNotSupported;
+    return switch (buf[2]) {
+        '0' => .http_1_0,
+        '1' => .http_1_1,
+        else => error.HttpVersionNotSupported,
+    };
 }
 
 fn parseHeaders(allocator: std.mem.Allocator, reader: anytype) !Headers {
     var map = Headers.init(allocator);
     errdefer map.deinit();
+    errdefer {
+        var iter = map.iterator();
+        while (iter.next()) |it| {
+            allocator.free(it.key_ptr.*);
+            allocator.free(it.value_ptr.*);
+        }
+    }
     // todo:
     //errdefer {
     //var iter = map.iterator();
@@ -167,6 +188,21 @@ fn parseEncoding(encoding: ?[]const u8) !Encoding {
     return error.UnsupportedMediaType;
 }
 
+pub fn parseFree(allocator: std.mem.Allocator, request: *Request) void {
+    allocator.free(request.uri);
+    freeHeaders(allocator, &request.headers);
+    if (request.body) |body| allocator.free(body);
+}
+
+fn freeHeaders(allocator: std.mem.Allocator, headers: *http.Headers) void {
+    var iter = headers.iterator();
+    while (iter.next()) |it| {
+        allocator.free(it.key_ptr.*);
+        allocator.free(it.value_ptr.*);
+    }
+    headers.deinit();
+}
+
 const _test = struct {
     const expectEqual = std.testing.expectEqual;
     const expectEqualStrings = std.testing.expectEqualStrings;

src/http/server.zig

@@ -2,67 +2,69 @@ const std = @import("std");
 const util = @import("util");
 const http = @import("./lib.zig");
 
-const connection = @import("./server/connection.zig");
 const response = @import("./server/response.zig");
 
-pub const Connection = connection.Connection;
-pub const Response = response.ResponseStream(Connection.Writer);
+pub const Response = struct {
+    alloc: std.mem.Allocator,
+    stream: std.net.Stream,
+    should_close: bool = false,
+    pub const Stream = response.ResponseStream(std.net.Stream.Writer);
+    pub fn open(self: *Response, status: http.Status, headers: *const http.Headers) !Stream {
+        if (headers.get("Connection")) |hdr| {
+            if (std.ascii.indexOfIgnoreCase(hdr, "close")) |_| self.should_close = true;
+        }
+
+        return response.open(self.alloc, self.stream.writer(), headers, status);
+    }
+};
 
-const ConnectionServer = connection.Server;
 const Request = http.Request;
 const request_buf_size = 1 << 16;
 
-pub const Context = struct {
-    alloc: std.mem.Allocator,
-    request: Request,
-    connection: Connection,
+pub fn Handler(comptime Ctx: type) type {
+    return fn (Ctx, Request, *Response) void;
+}
 
-    pub fn openResponse(self: *Context, headers: *const http.Headers, status: http.Status) !Response {
-        return try response.open(self.alloc, self.connection.stream.writer(), headers, status);
-    }
+pub fn serveConn(conn: std.net.StreamServer.Connection, ctx: anytype, handler: anytype, alloc: std.mem.Allocator) !void {
+    // TODO: Timeouts
+    while (true) {
+        std.log.debug("waiting for request", .{});
+        var arena = std.heap.ArenaAllocator.init(alloc);
+        defer arena.deinit();
 
-    pub fn close(self: *Context) void {
-        // todo: deallocate request
-        self.connection.close();
-    }
-};
-
-pub const Server = struct {
-    conn_server: ConnectionServer,
-    pub fn listen(addr: std.net.Address) !Server {
-        return Server{
-            .conn_server = try ConnectionServer.listen(addr),
+        const req = Request.parse(arena.allocator(), conn.stream.reader(), conn.address) catch |err| {
+            return handleError(conn.stream.writer(), err) catch {};
         };
+        std.log.debug("done parsing", .{});
+
+        var res = Response{
+            .alloc = arena.allocator(),
+            .stream = conn.stream,
+        };
+
+        handler(ctx, req, &res);
+        std.log.debug("done handling", .{});
+
+        if (req.headers.get("Connection")) |hdr| {
+            if (std.ascii.indexOfIgnoreCase(hdr, "close")) |_| return;
+        } else if (req.headers.get("Keep-Alive")) |hdr| {
+            std.log.debug("keep-alive: {s}", .{hdr});
+        } else if (req.protocol == .http_1_0) return;
+
+        if (res.should_close) return;
     }
+}
 
-    pub fn accept(self: *Server, alloc: std.mem.Allocator) !Context {
-        while (true) {
-            const conn = try self.conn_server.accept();
-            errdefer conn.close();
-
-            const req = http.Request.parse(alloc, conn.stream.reader()) catch |err| {
-                handleError(conn.stream.writer(), err) catch unreachable;
-                continue;
-            };
-
-            return Context{ .connection = conn, .request = req, .alloc = alloc };
-        }
-    }
-
-    pub fn shutdown(self: *Server) void {
-        self.conn_server.shutdown();
-    }
-};
-
-// TODO: We should get more specific about what type of errors can happen
+/// Writes an error response message and requests closure of the connection
 fn handleError(writer: anytype, err: anyerror) !void {
     const status: http.Status = switch (err) {
+        error.EndOfStream => return, // Do nothing, the client closed the connection
         error.BadRequest => .bad_request,
         error.UnsupportedMediaType => .unsupported_media_type,
         error.HttpVersionNotSupported => .http_version_not_supported,
 
-        else => return err,
+        else => .internal_server_error,
     };
 
-    try writer.print("HTTP/1.1 {} {?s}\r\n\r\n", .{ @enumToInt(status), status.phrase() });
+    try writer.print("HTTP/1.1 {} {?s}\r\nConnection: close\r\n\r\n", .{ @enumToInt(status), status.phrase() });
 }

src/http/server/connection.zig

@@ -1,51 +0,0 @@
-const std = @import("std");
-
-pub const Connection = struct {
-    pub const Id = u64;
-    pub const Writer = std.net.Stream.Writer;
-    pub const Reader = std.net.Stream.Reader;
-
-    id: Id,
-    address: std.net.Address,
-    stream: std.net.Stream,
-
-    fn new(id: Id, std_conn: std.net.StreamServer.Connection) Connection {
-        std.log.debug("new connection conn_id={}", .{id});
-        return .{
-            .id = id,
-            .address = std_conn.address,
-            .stream = std_conn.stream,
-        };
-    }
-
-    pub fn close(self: Connection) void {
-        std.log.debug("terminating connection conn_id={}", .{self.id});
-        self.stream.close();
-    }
-};
-
-pub const Server = struct {
-    next_conn_id: std.atomic.Atomic(Connection.Id) = std.atomic.Atomic(Connection.Id).init(1),
-    stream_server: std.net.StreamServer,
-
-    pub fn listen(addr: std.net.Address) !Server {
-        var self = Server{
-            .stream_server = std.net.StreamServer.init(.{ .reuse_address = true }),
-        };
-        errdefer self.stream_server.deinit();
-
-        try self.stream_server.listen(addr);
-        return self;
-    }
-
-    pub fn accept(self: *Server) !Connection {
-        const conn = try self.stream_server.accept();
-        const id = self.next_conn_id.fetchAdd(1, .SeqCst);
-
-        return Connection.new(id, conn);
-    }
-
-    pub fn shutdown(self: *Server) void {
-        self.stream_server.deinit();
-    }
-};

src/http/server/response.zig

@@ -111,9 +111,7 @@ pub fn ResponseStream(comptime BaseWriter: type) type {
         }
 
         fn flushBodyUnchunked(self: *Self) Error!void {
-            if (self.buffer_pos != 0) {
-                try self.base_writer.print("Content-Length: {}\r\n", .{self.buffer_pos});
-            }
+            try self.base_writer.print("Content-Length: {}\r\n", .{self.buffer_pos});
 
             try self.base_writer.writeAll("\r\n");
 
@@ -128,6 +126,7 @@ pub fn ResponseStream(comptime BaseWriter: type) type {
         }
 
         pub fn finish(self: *Self) Error!void {
+            std.log.debug("finishing", .{});
             if (!self.chunked) {
                 try self.flushBodyUnchunked();
             } else {

src/main/controllers.zig

@@ -13,14 +13,13 @@ pub const invites = @import("./controllers/invites.zig");
 pub const users = @import("./controllers/users.zig");
 pub const notes = @import("./controllers/notes.zig");
 
-pub fn routeRequest(api_source: anytype, ctx: http.server.Context, alloc: std.mem.Allocator) void {
+pub fn routeRequest(api_source: anytype, req: http.Request, res: *http.Response, alloc: std.mem.Allocator) void {
     // TODO: hashmaps?
-    inline for (routes) |route| {
-        if (Context(route).matchAndHandle(api_source, ctx, alloc)) return;
-    }
-
-    var response = Response{ .headers = http.Headers.init(alloc), .ctx = ctx };
+    var response = Response{ .headers = http.Headers.init(alloc), .res = res };
     defer response.headers.deinit();
+    inline for (routes) |route| {
+        if (Context(route).matchAndHandle(api_source, req, &response, alloc)) return;
+    }
 
     response.status(.not_found) catch {};
 }
@@ -53,7 +52,7 @@ pub fn Context(comptime Route: type) type {
         allocator: std.mem.Allocator,
 
         method: http.Method,
-        request_line: []const u8,
+        uri: []const u8,
         headers: http.Headers,
 
         args: Args,
@@ -84,20 +83,16 @@ pub fn Context(comptime Route: type) type {
             @compileError("Unsupported Type " ++ @typeName(T));
         }
 
-        pub fn matchAndHandle(api_source: *api.ApiSource, ctx: http.server.Context, alloc: std.mem.Allocator) bool {
-            const req = ctx.request;
+        pub fn matchAndHandle(api_source: *api.ApiSource, req: http.Request, res: *Response, alloc: std.mem.Allocator) bool {
             if (req.method != Route.method) return false;
-            var path = std.mem.sliceTo(std.mem.sliceTo(req.path, '#'), '?');
+            var path = std.mem.sliceTo(std.mem.sliceTo(req.uri, '#'), '?');
             var args: Args = parseArgs(path) orelse return false;
 
-            var response = Response{ .headers = http.Headers.init(alloc), .ctx = ctx };
-            defer response.headers.deinit();
-
             var self = Self{
                 .allocator = alloc,
 
                 .method = req.method,
-                .request_line = req.path,
+                .uri = req.uri,
                 .headers = req.headers,
 
                 .args = args,
@@ -105,7 +100,7 @@ pub fn Context(comptime Route: type) type {
                 .query = undefined,
             };
 
-            self.prepareAndHandle(api_source, req, &response);
+            self.prepareAndHandle(api_source, req, res);
 
             return true;
         }
@@ -149,15 +144,20 @@ pub fn Context(comptime Route: type) type {
 
         fn parseQuery(self: *Self) !void {
             if (Query != void) {
-                const path = std.mem.sliceTo(self.request_line, '?');
-                const q = std.mem.sliceTo(self.request_line[path.len..], '#');
+                const path = std.mem.sliceTo(self.uri, '?');
+                const q = std.mem.sliceTo(self.uri[path.len..], '#');
 
                 self.query = try query_utils.parseQuery(Query, q);
             }
         }
 
         fn handle(self: Self, response: *Response, api_conn: anytype) void {
-            Route.handler(self, response, api_conn) catch |err| std.log.err("{}", .{err});
+            Route.handler(self, response, api_conn) catch |err| switch (err) {
+                else => {
+                    std.log.err("{}", .{err});
+                    response.err(.internal_server_error, "", {}) catch {};
+                },
+            };
         }
 
         fn getApiConn(self: *Self, api_source: anytype) !api.ApiSource.Conn {
@@ -180,18 +180,25 @@ pub fn Context(comptime Route: type) type {
 pub const Response = struct {
     const Self = @This();
     headers: http.Headers,
-    ctx: http.server.Context,
+    res: *http.Response,
+    opened: bool = false,
 
     pub fn status(self: *Self, status_code: http.Status) !void {
-        var stream = try self.ctx.openResponse(&self.headers, status_code);
+        std.debug.assert(!self.opened);
+        self.opened = true;
+
+        var stream = try self.res.open(status_code, &self.headers);
         defer stream.close();
         try stream.finish();
     }
 
     pub fn json(self: *Self, status_code: http.Status, response_body: anytype) !void {
+        std.debug.assert(!self.opened);
+        self.opened = true;
+
         try self.headers.put("Content-Type", "application/json");
 
-        var stream = try self.ctx.openResponse(&self.headers, status_code);
+        var stream = try self.res.open(status_code, &self.headers);
         defer stream.close();
 
         const writer = stream.writer();

src/main/main.zig

@@ -8,36 +8,8 @@ const api = @import("api");
 pub const migrations = @import("./migrations.zig"); // TODO
 const c = @import("./controllers.zig");
 
-pub const RequestServer = struct {
-    alloc: std.mem.Allocator,
-    api: *api.ApiSource,
-    config: Config,
-
-    fn init(alloc: std.mem.Allocator, src: *api.ApiSource, config: Config) !RequestServer {
-        return RequestServer{
-            .alloc = alloc,
-            .api = src,
-            .config = config,
-        };
-    }
-
-    fn listenAndRun(self: *RequestServer, addr: std.net.Address) !void {
-        var srv = http.Server.listen(addr) catch unreachable;
-        defer srv.shutdown();
-
-        while (true) {
-            var arena = std.heap.ArenaAllocator.init(self.alloc);
-            defer arena.deinit();
-
-            var ctx = try srv.accept(arena.allocator());
-            defer ctx.close();
-
-            c.routeRequest(self.api, ctx, arena.allocator());
-        }
-    }
-};
-
 pub const Config = struct {
+    worker_threads: usize = 10,
     db: sql.Config,
 };
 
@@ -64,7 +36,10 @@ fn runAdminSetup(db: sql.Db, alloc: std.mem.Allocator) !void {
     try api.setupAdmin(db, origin, username, password, alloc);
 }
 
-fn prepareDb(db: sql.Db, alloc: std.mem.Allocator) !void {
+fn prepareDb(pool: *sql.ConnPool, alloc: std.mem.Allocator) !void {
+    const db = try pool.acquire();
+    defer db.releaseConnection();
+
     try migrations.up(db);
 
     if (!try api.isAdminSetup(db)) {
@@ -88,15 +63,46 @@ fn prepareDb(db: sql.Db, alloc: std.mem.Allocator) !void {
     }
 }
 
+const ConnectionId = u64;
+var next_conn_id = std.atomic.Atomic(ConnectionId).init(0);
+
+fn thread_main(src: *api.ApiSource, srv: *std.net.StreamServer) void {
+    util.seedThreadPrng() catch unreachable;
+    const thread_id = std.Thread.getCurrentId();
+    var gpa = std.heap.GeneralPurposeAllocator(.{}){};
+
+    while (true) {
+        var conn = srv.accept() catch |err| {
+            std.log.err("Error accepting connection: {}", .{err});
+            continue;
+        };
+        defer conn.stream.close();
+        const conn_id = next_conn_id.fetchAdd(1, .SeqCst);
+        std.log.debug("Accepting TCP connection id {} on thread {}", .{ conn_id, thread_id });
+        defer std.log.debug("Closing TCP connection id {}", .{conn_id});
+
+        http.serveConn(conn, .{ .src = src, .conn_id = conn_id, .allocator = gpa.allocator() }, handle, gpa.allocator()) catch |err| {
+            std.log.err("Error occured on connection {}: {}", .{ conn_id, err });
+        };
+    }
+}
+
+fn handle(ctx: anytype, req: http.Request, res: *http.Response) void {
+    c.routeRequest(ctx.src, req, res, ctx.allocator);
+}
+
 pub fn main() !void {
     try util.seedThreadPrng();
 
     var gpa = std.heap.GeneralPurposeAllocator(.{}){};
     var cfg = try loadConfig(gpa.allocator());
-    var db_conn = try sql.Conn.open(cfg.db);
-    try prepareDb(try db_conn.acquire(), gpa.allocator());
+    var pool = try sql.ConnPool.init(cfg.db);
+    try prepareDb(&pool, gpa.allocator());
 
-    var api_src = try api.ApiSource.init(&db_conn);
-    var srv = try RequestServer.init(gpa.allocator(), &api_src, cfg);
-    return srv.listenAndRun(std.net.Address.parseIp("0.0.0.0", 8080) catch unreachable);
+    var api_src = try api.ApiSource.init(&pool);
+    var srv = std.net.StreamServer.init(.{ .reuse_address = true });
+    defer srv.deinit();
+    try srv.listen(std.net.Address.parseIp("0.0.0.0", 8080) catch unreachable);
+
+    thread_main(&api_src, &srv);
 }

src/main/migrations.zig

@@ -16,10 +16,15 @@ fn execStmt(tx: anytype, stmt: []const u8, alloc: std.mem.Allocator) !void {
 }
 
 fn execScript(db: anytype, script: []const u8, alloc: std.mem.Allocator) !void {
+    const tx = try db.beginOrSavepoint();
+    errdefer tx.rollback();
+
     var iter = util.SqlStmtIter.from(script);
     while (iter.next()) |stmt| {
-        try execStmt(db, stmt, alloc);
+        try execStmt(tx, stmt, alloc);
     }
+
+    try tx.commitOrRelease();
 }
 
 fn wasMigrationRan(db: anytype, name: []const u8, alloc: std.mem.Allocator) !bool {

src/sql/engines/null.zig

@@ -28,6 +28,10 @@ pub const Db = struct {
         unreachable;
     }
 
+    pub fn openUri(_: anytype) common.OpenError!Db {
+        unreachable;
+    }
+
     pub fn close(_: Db) void {
         unreachable;
     }

src/sql/engines/sqlite.zig

@@ -49,7 +49,15 @@ pub const Db = struct {
     db: *c.sqlite3,
 
     pub fn open(path: [:0]const u8) common.OpenError!Db {
-        const flags = c.SQLITE_OPEN_READWRITE | c.SQLITE_OPEN_CREATE | c.SQLITE_OPEN_EXRESCODE;
+        return openInternal(path, false);
+    }
+
+    pub fn openUri(path: [:0]const u8) common.OpenError!Db {
+        return openInternal(path, true);
+    }
+
+    fn openInternal(path: [:0]const u8, is_uri: bool) common.OpenError!Db {
+        const flags = c.SQLITE_OPEN_READWRITE | c.SQLITE_OPEN_CREATE | c.SQLITE_OPEN_EXRESCODE | if (is_uri) c.SQLITE_OPEN_URI else 0;
 
         var db: ?*c.sqlite3 = null;
         switch (c.sqlite3_open_v2(@ptrCast([*c]const u8, path), &db, flags, null)) {
@@ -121,7 +129,6 @@ pub const Db = struct {
                 // of 0, and we must not bind the argument.
                 const name = std.fmt.comptimePrint("${}", .{i + 1});
                 const db_idx = c.sqlite3_bind_parameter_index(stmt.?, name);
-                std.log.debug("param {s} got index {}", .{ name, db_idx });
                 if (db_idx != 0)
                     try self.bindArgument(stmt.?, @intCast(u15, db_idx), arg)
                 else if (!opts.ignore_unused_arguments)
@@ -167,7 +174,6 @@ pub const Db = struct {
                 else
                     @compileError("SQLite: Could not serialize " ++ @typeName(T) ++ " into staticly sized string");
 
-                std.log.debug("binding type {any}: {s}", .{ T, arr });
                 const len = std.mem.len(&arr);
                 return self.bindString(stmt, idx, arr[0..len]);
             },
@@ -194,8 +200,6 @@ pub const Db = struct {
             return error.BindException;
         };
 
-        std.log.debug("binding string {s} to idx {}", .{ str, idx });
-
         switch (c.sqlite3_bind_text(stmt, idx, str.ptr, len, c.SQLITE_TRANSIENT)) {
             c.SQLITE_OK => {},
             else => |result| {

src/sql/lib.zig

@@ -10,6 +10,7 @@ const Allocator = std.mem.Allocator;
 
 const errors = @import("./errors.zig").library_errors;
 
+pub const AcquireError = OpenError || error{NoConnectionsLeft};
 pub const OpenError = errors.OpenError;
 pub const QueryError = errors.QueryError;
 pub const RowError = errors.RowError;
@@ -24,12 +25,14 @@ pub const Engine = enum {
     sqlite,
 };
 
+// TODO: make this suck less
 pub const Config = union(Engine) {
     postgres: struct {
         pg_conn_str: [:0]const u8,
     },
     sqlite: struct {
         sqlite_file_path: [:0]const u8,
+        sqlite_is_uri: bool = false,
     },
 };
 
@@ -160,16 +163,58 @@ pub const ConstraintMode = enum {
     immediate,
 };
 
-pub const Conn = struct {
-    engine: union(Engine) {
-        postgres: postgres.Db,
-        sqlite: sqlite.Db,
-    },
-    current_tx_level: u8 = 0,
-    is_tx_failed: bool = false,
+pub const ConnPool = struct {
+    const max_conns = 4;
+    const Conn = struct {
+        engine: union(Engine) {
+            postgres: postgres.Db,
+            sqlite: sqlite.Db,
+        },
+        in_use: std.atomic.Atomic(bool) = std.atomic.Atomic(bool).init(false),
+        current_tx_level: u8 = 0,
+    };
 
-    pub fn open(cfg: Config) OpenError!Conn {
-        return switch (cfg) {
+    config: Config,
+    connections: [max_conns]Conn,
+
+    pub fn init(cfg: Config) OpenError!ConnPool {
+        var self = ConnPool{
+            .config = cfg,
+            .connections = undefined,
+        };
+        var count: usize = 0;
+        errdefer for (self.connections[0..count]) |*c| closeConn(c);
+        for (self.connections) |*c| {
+            c.* = try self.createConn();
+            count += 1;
+        }
+
+        return self;
+    }
+
+    pub fn deinit(self: *ConnPool) void {
+        for (self.connections) |*c| closeConn(c);
+    }
+
+    pub fn acquire(self: *ConnPool) AcquireError!Db {
+        for (self.connections) |*c| {
+            if (tryAcquire(c)) return Db{ .conn = c };
+        }
+        return error.NoConnectionsLeft;
+    }
+
+    fn tryAcquire(conn: *Conn) bool {
+        const acquired = !conn.in_use.swap(true, .AcqRel);
+        if (acquired) {
+            if (conn.current_tx_level != 0) @panic("Transaction still open on unused db connection");
+            return true;
+        }
+
+        return false;
+    }
+
+    fn createConn(self: *ConnPool) OpenError!Conn {
+        return switch (self.config) {
             .postgres => |postgres_cfg| Conn{
                 .engine = .{
                     .postgres = try postgres.Db.open(postgres_cfg.pg_conn_str),
@@ -177,27 +222,22 @@ pub const Conn = struct {
             },
             .sqlite => |lite_cfg| Conn{
                 .engine = .{
-                    .sqlite = try sqlite.Db.open(lite_cfg.sqlite_file_path),
+                    .sqlite = if (lite_cfg.sqlite_is_uri)
+                        try sqlite.Db.openUri(lite_cfg.sqlite_file_path)
+                    else
+                        try sqlite.Db.open(lite_cfg.sqlite_file_path),
                 },
             },
         };
     }
 
-    pub fn close(self: *Conn) void {
-        switch (self.engine) {
+    fn closeConn(conn: *Conn) void {
+        if (conn.in_use.loadUnchecked()) @panic("DB Conn still open");
+        switch (conn.engine) {
             .postgres => |pg| pg.close(),
             .sqlite => |lite| lite.close(),
         }
     }
-
-    pub fn acquire(self: *Conn) !Db {
-        if (self.current_tx_level != 0) return error.BadTransactionState;
-        return Db{ .conn = self };
-    }
-
-    pub fn sqlEngine(self: *Conn) Engine {
-        return self.engine;
-    }
 };
 
 pub const Db = Tx(0);
@@ -216,11 +256,22 @@ fn Tx(comptime tx_level: u8) type {
             std.fmt.comptimePrint("save_{}", .{tx_level});
         const next_savepoint_name = Tx(tx_level + 1).savepoint_name;
 
-        conn: *Conn,
+        conn: *ConnPool.Conn,
 
         /// The type of SQL engine being used. Use of this function should be discouraged
         pub fn sqlEngine(self: Self) Engine {
-            return self.conn.sqlEngine();
+            return self.conn.engine;
+        }
+
+        /// Return the connection to the pool
+        pub fn releaseConnection(self: Self) void {
+            if (tx_level != 0) @compileError("close must be called on root db");
+            if (self.conn.current_tx_level != 0) {
+                std.log.warn("Database released while transaction in progress!", .{});
+                self.rollbackUnchecked() catch {};
+            }
+
+            if (!self.conn.in_use.swap(false, .AcqRel)) @panic("Double close on db conection");
         }
 
         // ********* Transaction management functions **********
@@ -277,7 +328,7 @@ fn Tx(comptime tx_level: u8) type {
             if (tx_level >= 2) @compileError("Cannot rollback a transaction using a savepoint");
             if (self.conn.current_tx_level == 0) return error.BadTransactionState;
 
-            try self.exec("ROLLBACK", {}, null);
+            try self.rollbackUnchecked();
 
             self.conn.current_tx_level = 0;
         }
@@ -402,7 +453,7 @@ fn Tx(comptime tx_level: u8) type {
             comptime var table_spec: []const u8 = table ++ "(";
             comptime var value_spec: []const u8 = "(";
             inline for (fields) |field, i| {
-                // This causes a compile error. Why?
+                // This causes a compiler crash. Why?
                 //const F = field.field_type;
                 const F = @TypeOf(@field(std.mem.zeroes(ValueType), field.name));
                 // causes issues if F is @TypeOf(null), use dummy type
@@ -453,5 +504,9 @@ fn Tx(comptime tx_level: u8) type {
 
             while (try results.row()) |_| {}
         }
+
+        fn rollbackUnchecked(self: Self) !void {
+            try self.exec("ROLLBACK", {}, null);
+        }
     };
 }

tests/api_integration/lib.zig

@@ -5,11 +5,10 @@ const sql = @import("sql");
 const util = @import("util");
 
 const test_config = .{
-    .db = .{
-        .sqlite = .{
-            .sqlite_file_path = ":memory:",
-        },
-    },
+    .db = .{ .sqlite = .{
+        .sqlite_file_path = "file::memory:?cache=shared",
+        .sqlite_is_uri = true,
+    } },
 };
 
 const ApiSource = api.ApiSource;
@@ -18,12 +17,16 @@ const root_password = "password1234";
 const admin_host = "example.com";
 const admin_origin = "https://" ++ admin_host;
 
-fn makeDb(alloc: std.mem.Allocator) !sql.Conn {
+fn makeDb(alloc: std.mem.Allocator) !sql.ConnPool {
     try util.seedThreadPrng();
-    var db = try sql.Conn.open(test_config.db);
-    try migrations.up(try db.acquire());
-    try api.setupAdmin(try db.acquire(), admin_origin, root_user, root_password, alloc);
-    return db;
+    var pool = try sql.ConnPool.init(test_config.db);
+    {
+        var db = try pool.acquire();
+        defer db.releaseConnection();
+        try migrations.up(db);
+        try api.setupAdmin(db, admin_origin, root_user, root_password, alloc);
+    }
+    return pool;
 }
 
 fn connectAndLogin(
@@ -42,6 +45,7 @@ fn connectAndLogin(
 test "login as root" {
     const alloc = std.testing.allocator;
     var db = try makeDb(alloc);
+    defer db.deinit();
     var src = try ApiSource.init(&db);
 
     const login = try connectAndLogin(&src, admin_host, root_user, root_password, alloc);
@@ -59,6 +63,7 @@ test "login as root" {
 test "create community" {
     const alloc = std.testing.allocator;
     var db = try makeDb(alloc);
+    defer db.deinit();
     var src = try ApiSource.init(&db);
 
     const login = try connectAndLogin(&src, admin_host, root_user, root_password, alloc);
@@ -80,6 +85,7 @@ test "create community" {
 test "create community and transfer to new owner" {
     const alloc = std.testing.allocator;
     var db = try makeDb(alloc);
+    defer db.deinit();
     var src = try ApiSource.init(&db);
 
     const root_login = try connectAndLogin(&src, admin_host, root_user, root_password, alloc);