wasi-common: switch all logs from log to tracing

tracing is already the dep that wiggle uses.

I used tracing structured arguments wherever I could, but I skipped over
it in all of the snapshot_0 code, because I'm going to delete that code
and replace it with wiggle-based stuff real soon.

crates/wasi-common/src/snapshots/wasi_snapshot_preview1.rs

@@ -5,9 +5,9 @@ use crate::wasi::wasi_snapshot_preview1::WasiSnapshotPreview1;
 use crate::wasi::{types, AsBytes, Errno, Result};
 use crate::WasiCtx;
 use crate::{path, poll};
-use log::{debug, error, trace};
 use std::convert::TryInto;
 use std::io::{self, SeekFrom};
+use tracing::{debug, error, trace};
 use wiggle::{GuestPtr, GuestSlice};
 
 impl<'a> WasiSnapshotPreview1 for WasiCtx {
@@ -651,7 +651,7 @@ impl<'a> WasiSnapshotPreview1 for WasiCtx {
             true,
         )?;
         let old_path = old_path.as_str()?;
-        trace!("     | old_path='{}'", &*old_path);
+        trace!(old_path = &*old_path);
         new_fd.symlink(&old_path, &new_path)
     }
 
@@ -701,8 +701,11 @@ impl<'a> WasiSnapshotPreview1 for WasiCtx {
             match subscription.u {
                 types::SubscriptionU::Clock(clock) => {
                     let delay = clock::to_relative_ns_delay(&clock)?;
-                    debug!("poll_oneoff event.u.clock = {:?}", clock);
-                    debug!("poll_oneoff delay = {:?}ns", delay);
+                    debug!(
+                        clock = tracing::field::debug(&clock),
+                        delay_ns = tracing::field::debug(delay),
+                        "poll_oneoff"
+                    );
                     let current = poll::ClockEventData {
                         delay,
                         userdata: subscription.userdata,
@@ -766,8 +769,11 @@ impl<'a> WasiSnapshotPreview1 for WasiCtx {
                 }
             }
         }
-        debug!("poll_oneoff events = {:?}", events);
-        debug!("poll_oneoff timeout = {:?}", timeout);
+        debug!(
+            events = tracing::field::debug(&events),
+            timeout = tracing::field::debug(timeout),
+            "poll_oneoff"
+        );
         // The underlying implementation should successfully and immediately return
         // if no events have been passed. Such situation may occur if all provided
         // events have been filtered out as errors in the code above.
@@ -780,7 +786,7 @@ impl<'a> WasiSnapshotPreview1 for WasiCtx {
             event_ptr.write(event)?;
         }
 
-        trace!("     | *nevents={:?}", nevents);
+        trace!(nevents = nevents);
 
         Ok(nevents)
     }
@@ -803,7 +809,7 @@ impl<'a> WasiSnapshotPreview1 for WasiCtx {
     fn random_get(&self, buf: &GuestPtr<u8>, buf_len: types::Size) -> Result<()> {
         let mut slice = buf.as_array(buf_len).as_slice()?;
         getrandom::getrandom(&mut *slice).map_err(|err| {
-            error!("getrandom failure: {:?}", err);
+            error!(error = tracing::field::display(err), "getrandom failure");
             Errno::Io
         })
     }