Rework using the POSIX syslog API. This is a breaking change.

As discussed in PR slog-rs#5, this is based on the [syslog backend that I wrote for sloggers][1] and does not use the `syslog` crate. It is now very different from both slog-syslog 0.12 and PR slog-rs#5. Differences from slog-rs#5 include:

* Uses the POSIX syslog API through the `libc` crate. (See “design and rationale” in src/lib.rs, starting at line 52, for details.) This means:
* Only works on Unix-like platforms.
* Only sends log messages to the local syslog daemon, not to a remote server.
* Formats log messages into a reusable thread-local buffer, as in slog-syslog 0.12.
* The `Drain` implementation is now called `SyslogDrain` instead of `Streamer3164`, since local syslog doesn't use the RFC3164 protocol.
* If the `serde` feature is enabled, logging settings can be loaded from a configuration file.

Minimum supported Rust version is 1.27.2, or if the `serde` feature is enabled, 1.31.0. Doc-tests require 1.28.0. Works (except doc-tests) on 1.26.2 if you run the following commands first:

```
cargo generate-lockfile
cargo update --package lazy_static --precise 1.3.0
cargo update --package serde --precise 1.0.58
cargo update --package serde_derive --precise 1.0.58
```

[1]: sile/sloggers#34

Author: argv-minus-one

Cargo.toml

@@ -1,19 +1,23 @@
 [package]
 name = "slog-syslog"
-version = "0.12.0"
+version = "0.13.0"
 authors = ["Dawid Ciężarkiewicz <dpc@dpc.pw>", "William Laeder <codylaeder@gmail.com" ]
 description = "Syslog drain for slog-rs"
 keywords = ["slog", "logging", "json", "log", "syslog"]
 license = "MPL-2.0"
-documentation = "https://docs.rs/slog-rs/term"
+documentation = "https://docs.rs/slog-syslog"
 homepage = "https://github.com/slog-rs/slog"
 repository = "https://github.com/slog-rs/syslog"
 readme = "README.md"
 
-[lib]
-path = "lib.rs"
-
 [dependencies]
+lazy_static = "1"
+libc = "0.2"
+serde = { version = "1", optional = true, features = ["derive"] }
 slog = "^2.1.1"
-syslog = "3.3.0"
-nix = "0.14.0"
+
+[dev-dependencies]
+toml = "0.4"
+
+[package.metadata.docs.rs]
+all-features = true

Makefile

@@ -15,25 +15,29 @@ CARGO_FLAGS += --release
 else
 $(info DEBUG BUILD: $(PKG_NAME); use `RELEASE=true make [args]` for release build)
 endif
+CARGO_FEATURES=serde
 
 EXAMPLES = $(shell cd examples 2>/dev/null && ls *.rs 2>/dev/null | sed -e 's/.rs$$//g' )
 
 all: $(ALL_TARGETS)
 
 .PHONY: run test build doc clean clippy
-run test build clean:
+run test build:
+	cargo $@ --features $(CARGO_FEATURES) $(CARGO_FLAGS)
+
+clean:
 	cargo $@ $(CARGO_FLAGS)
 
 check:
 	$(info Running check; use `make build` to actually build)
-	cargo $@ $(CARGO_FLAGS)
+	cargo $@ --features $(CARGO_FEATURES) $(CARGO_FLAGS)
 
 clippy:
-	cargo build --features clippy
+	cargo build --features clippy,$(CARGO_FEATURES)
 
 .PHONY: bench
 bench:
-	cargo $@ $(filter-out --release,$(CARGO_FLAGS))
+	cargo $@ --features $(CARGO_FEATURES) $(filter-out --release,$(CARGO_FLAGS))
 
 .PHONY: travistest
 travistest: test
@@ -50,7 +54,7 @@ $(EXAMPLES):
 
 .PHONY: doc
 doc: FORCE
-	cargo doc
+	cargo --features $(CARGO_FEATURES) doc
 
 .PHONY: publishdoc
 publishdoc:

examples/syslog-unix.rs

@@ -2,12 +2,11 @@
 extern crate slog;
 extern crate slog_syslog;
 
-use slog::Drain;
-use slog_syslog::Facility;
+use slog_syslog::{Facility, SyslogBuilder};
 
 fn main() {
-    let syslog = slog_syslog::unix_3164(Facility::LOG_USER).unwrap();
-    let root = slog::Logger::root(syslog.fuse(), o!());
+    let syslog = SyslogBuilder::new().facility(Facility::User).build();
+    let root = slog::Logger::root(syslog, o!());
 
     info!(root, "Starting");