Make logging optional via 'log' feature.

Cargo.toml

@@ -22,9 +22,9 @@ default = []
 all = ["json"]
 json = ["serde", "serde_json"]
 tokio-io = ["tokio", "tokio-util"]
+log = ["dep:log"]
 
 [dependencies]
-log = "0.4.15"
 bytes = "1.0"
 futures-util = { version = "0.3", default-features = false }
 memchr = "2.4"
@@ -34,6 +34,7 @@ mime = "0.3.10"
 encoding_rs = "0.8.20"
 spin = { version = "0.9", default-features = false, features = ["spin_mutex"] }
 
+log = { version = "0.4.15", optional = true }
 serde = { version = "1.0", optional = true }
 serde_json = { version = "1.0", optional = true }
 tokio = { version = "1.0", features = [],  optional = true }

src/buffer.rs

@@ -95,9 +95,9 @@ impl<'r> StreamBuffer<'r> {
         boundary: &str,
         field_name: Option<&str>,
     ) -> crate::Result<Option<(bool, Bytes)>> {
-        log::trace!("finding next field: {:?}", field_name);
+        trace!("finding next field: {:?}", field_name);
         if self.buf.is_empty() && self.eof {
-            log::trace!("empty buffer && EOF");
+            trace!("empty buffer && EOF");
             return Err(crate::Error::IncompleteFieldData {
                 field_name: field_name.map(|s| s.to_owned()),
             });
@@ -110,7 +110,7 @@ impl<'r> StreamBuffer<'r> {
 
         match memchr::memmem::find(&self.buf, boundary_deriv.as_bytes()) {
             Some(idx) => {
-                log::trace!("new field found at {}", idx);
+                trace!("new field found at {}", idx);
                 let bytes = self.buf.split_to(idx).freeze();
 
                 // discard \r\n.
@@ -119,7 +119,7 @@ impl<'r> StreamBuffer<'r> {
                 Ok(Some((true, bytes)))
             }
             None if self.eof => {
-                log::trace!("no new field found: EOF. terminating");
+                trace!("no new field found: EOF. terminating");
                 Err(crate::Error::IncompleteFieldData {
                     field_name: field_name.map(|s| s.to_owned()),
                 })
@@ -133,7 +133,7 @@ impl<'r> StreamBuffer<'r> {
                     0
                 };
 
-                log::trace!("no new field found, not EOF, checking close");
+                trace!("no new field found, not EOF, checking close");
                 let bytes = &self.buf[rem_boundary_part_idx..];
                 match memchr::memmem::rfind(bytes, constants::CR.as_bytes()) {
                     Some(rel_idx) => {

src/lib.rs

@@ -5,6 +5,8 @@
 //! `AsyncRead` reader as a source, so that it can be plugged into any async
 //! Rust environment e.g. any async server.
 //!
+//! To enable trace logging via the `log` crate, enable the `log` feature.
+//!
 //! # Examples
 //!
 //! ```no_run
@@ -125,6 +127,16 @@ pub use field::Field;
 pub use multipart::Multipart;
 pub use size_limit::SizeLimit;
 
+#[cfg(feature = "log")]
+macro_rules! trace {
+    ($($t:tt)*) => (::log::trace!($($t)*););
+}
+
+#[cfg(not(feature = "log"))]
+macro_rules! trace {
+    ($($t:tt)*) => {};
+}
+
 mod buffer;
 mod constants;
 mod constraints;