update README

README.md

@@ -26,13 +26,33 @@ library can be found in src/main-lib.zig.
 Architecture
 ------------
 
-TODO:
+This library assumes the use of Linux as a host. While the primary engine is not
+tied to Linux, the file watcher module uses inotify and friends and will not
+work outside that OS. PRs are welcome.
 
-We assume Linux.
+The system is built with a pre-release version of zig, currently zig version
+[0.11.0-dev.3312+ab37ab33c](https://github.com/marler8997/zig-unofficial-releases#0110-dev3312ab37ab33c-summary).
+This version has web server in the standard library, so it is useful.
 
-Built with zig 0.11.0-dev.3312+ab37ab33c (provide permalink). Explain lock to 0.11 when released.
+To achieve the lowest latency possible, this server loads dynamic libraries
+using [dlopen(3)](https://linux.die.net/man/3/dlopen) based on a configuration
+file in the current working directory called `proxy.ini`. An example of the
+configuration is in this directory, and it is relatively simple string prefix
+matching, again, for speed.
 
-To achieve the lowest latency possible and eliminate the proliferation, The architecture of this server is setup 
+On startup, a thread pool will be created. Request paths and header matching
+is loaded from the configuration file, and file watches are initiated on all
+libraries mentioned in the configuration file. Libraries are loaded on demand
+when a request arrives that needs the library. When a library changes for a new
+version, the file watcher will take note and unload the previous version.
+
+Changes to the configuration file are not watched, relying instead on a HUP
+signal to force a reload. At that point, all libraries ("executors") are
+unloaded, and configuration is re-read.
+
+As libraries are loaded directly into main process space, bugs in the libraries
+can and will crash the engine. As such, some supervisory process (dockerd,
+systemd, etc) should monitor and restart if necessary.
 
 Security
 --------
@@ -53,11 +73,13 @@ reported by the system (although thread count is limited to 4 threads when
 compiled in debug mode). This can be controlled with the environment variable
 `SERVER_THREAD_COUNT`.
 
-Future plans include an environment variable for IP address and port to listen
-on, as well as the amount of pre-allocated memory for response data (currently
-hardcoded to 1k/thread). Pre-allocated memory reduces the number of system
+The port by default is 8069, although this can be set with the `PORT`
+environment variable. Future plans include an environment variable for IP
+address as well as the amount of pre-allocated memory for response data (currently
+hardcoded to 8k/thread). Pre-allocated memory reduces the number of system
 calls required for memory allocation, and pre-allocation/allocation statistics
-per request are reported in the logs.
+per request are reported in the logs. The current pre-allocation provides
+approximately 4k per request without requiring system calls.
 
 Logs
 ----

build.zig

@@ -16,7 +16,7 @@ pub fn build(b: *std.Build) void {
     const optimize = b.standardOptimizeOption(.{});
 
     const exe = b.addExecutable(.{
-        .name = "faas-proxy",
+        .name = "flexilib",
         // In this case the main source file is merely a path, however, in more
         // complicated build scripts, this could be a generated file.
         .root_source_file = .{ .path = "src/main.zig" },
@@ -27,7 +27,7 @@ pub fn build(b: *std.Build) void {
     exe.linkLibC();
 
     const lib = b.addSharedLibrary(.{
-        .name = "faas-proxy-sample-lib",
+        .name = "flexilib-sample-lib",
         // In this case the main source file is merely a path, however, in more
         // complicated build scripts, this could be a generated file.
         .root_source_file = .{ .path = "src/main-lib.zig" },
@@ -37,7 +37,7 @@ pub fn build(b: *std.Build) void {
     lib.linkLibC();
 
     const interface_lib = b.addStaticLibrary(.{
-        .name = "libfaasproxy",
+        .name = "flexilib",
         // In this case the main source file is merely a path, however, in more
         // complicated build scripts, this could be a generated file.
         .root_source_file = .{ .path = "src/interface.zig" },

proxy.ini

@@ -6,6 +6,6 @@
 
 # Example of match based on an HTTP header. The key is space-delimited:
 # <http header key>: <header match prefix> <path match prefix>
-Host: iam / = zig-out/lib/libfaas-proxy-sample-lib.so
-/c = zig-out/lib/libfaas-proxy-sample-lib-in-c.so
-/ = zig-out/lib/libfaas-proxy-sample-lib.so
+Host: iam / = zig-out/lib/libflexilib-sample-lib.so
+/c = zig-out/lib/libflexilib-in-c.so
+/ = zig-out/lib/libflexilib-sample-lib.so

src/interface.zig

@@ -28,7 +28,7 @@ pub const Request = extern struct {
 };
 
 // If the library is Zig, we can use these helpers
-var allocator: ?*std.mem.Allocator = null;
+threadlocal var allocator: ?*std.mem.Allocator = null;
 
 const log = std.log.scoped(.interface);
 
@@ -120,7 +120,6 @@ pub fn handleRequest(request: *Request, zigRequestHandler: ZigRequestHandler) ?*
         return null;
     };
 
-    log.debug("response ptr: {*}", .{response.items.ptr});
     // Marshall data back for handling by server
 
     var rc = alloc.create(Response) catch {

src/main.zig

@@ -362,7 +362,10 @@ pub fn main() !void {
     var server = std.http.Server.init(allocator, .{ .reuse_address = true });
     defer server.deinit();
 
-    const address = try std.net.Address.parseIp("0.0.0.0", PORT);
+    const address = try std.net.Address.parseIp(
+        "0.0.0.0",
+        if (std.os.getenv("PORT")) |p| try std.fmt.parseInt(u16, p, 10) else PORT,
+    );
     try server.listen(address);
     const server_port = server.socket.listen_address.in.getPort();
     log.info("listening on port: {d}", .{server_port});