log which command is being run in spawning file adapters

src/adapters/spawning.rs

@@ -1,6 +1,7 @@
 use super::*;
 use encoding_rs_io::DecodeReaderBytesBuilder;
 use failure::*;
+use log::*;
 use std::io::prelude::*;
 use std::io::BufReader;
 use std::process::Command;
@@ -117,9 +118,11 @@ where
             ..
         } = ai;
         let cmd = Command::new(self.get_exe());
+        let cmd = self.command(filepath_hint, cmd);
+        debug!("executing {:?}", cmd);
         pipe_output(
             line_prefix,
-            self.command(filepath_hint, cmd),
+            cmd,
             &mut inp,
             oup,
             self.get_exe(),

src/matching.rs

@@ -11,7 +11,7 @@ use std::iter::Iterator;
 
 use std::rc::Rc;
 
-#[derive(Clone)]
+#[derive(Clone, Debug)]
 pub enum FastMatcher {
     // MimeType(Regex),
     /**
@@ -23,7 +23,7 @@ pub enum FastMatcher {
     // todo: maybe allow matching a directory (e.g. /var/lib/postgres)
 }
 
-#[derive(Clone)]
+#[derive(Clone, Debug)]
 pub enum SlowMatcher {
     /// any type of fast matcher
     Fast(FastMatcher),

src/preproc.rs

@@ -65,6 +65,10 @@ pub fn rga_preproc(ai: AdaptInfo) -> Fallible<()> {
     match adapter {
         Some((adapter, detection_reason)) => {
             let meta = adapter.metadata();
+            debug!(
+                "chose adapter '{}' because of matcher {:?}",
+                &meta.name, &detection_reason
+            );
             eprintln!("adapter: {}", &meta.name);
             let db_name = format!("{}.v{}", meta.name, meta.version);
             if let Some(cache) = cache.as_mut() {