cleanup: avoid allocation for log levels that aren't enabled (#67)

src/extism.rs

@@ -24,6 +24,7 @@ extern "C" {
     pub fn log_warn(offs: u64);
     pub fn log_error(offs: u64);
     pub fn log_trace(offs: u64);
+    pub fn get_log_level() -> i32;
 }
 
 /// Loads a byte array from Extism's memory. Only use this if you

src/lib.rs

@@ -43,11 +43,23 @@ pub type SharedFnResult<T> = Result<T, Error>;
 /// Logging levels
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
 pub enum LogLevel {
-    Info,
+    Trace,
     Debug,
+    Info,
     Warn,
     Error,
-    Trace,
+}
+
+impl LogLevel {
+    pub const fn to_int(self) -> i32 {
+        match self {
+            LogLevel::Trace => 0,
+            LogLevel::Debug => 1,
+            LogLevel::Info => 2,
+            LogLevel::Warn => 3,
+            LogLevel::Error => 4,
+        }
+    }
 }
 
 /// Re-export of `serde_json`

src/macros.rs

@@ -1,9 +1,12 @@
 #[macro_export]
 macro_rules! log {
     ($lvl:expr, $($arg:tt)+) => {{
-        let fmt = format!($($arg)+);
-        let memory = $crate::Memory::from_bytes(&fmt).unwrap();
-        memory.log($lvl)
+        let level = unsafe { $crate::extism::get_log_level() };
+        if $lvl.to_int() >= level && level != i32::MAX  {
+            let fmt = format!($($arg)+);
+            let memory = $crate::Memory::from_bytes(&fmt).unwrap();
+            memory.log($lvl)
+        }
     }}
 }