better errors

src/bin/rga-preproc.rs

@@ -2,6 +2,7 @@ use rga::adapters::*;
 use rga::preproc::*;
 use ripgrep_all as rga;
 
+use anyhow::Context;
 use std::fs::File;
 
 fn main() -> anyhow::Result<()> {
@@ -20,7 +21,7 @@ fn main() -> anyhow::Result<()> {
     let cache = if args.no_cache {
         None
     } else {
-        Some(rga::preproc_cache::open()?)
+        Some(rga::preproc_cache::open().context("could not open cache")?)
     };
     let ai = AdaptInfo {
         inp: &mut i,

src/preproc.rs

@@ -106,18 +106,26 @@ pub fn rga_preproc(ai: AdaptInfo) -> Result<()> {
                             args.cache_compression_level.try_into().unwrap(),
                         )?);
                         debug!("adapting...");
-                        adapter.adapt(
-                            AdaptInfo {
-                                line_prefix,
-                                filepath_hint,
-                                is_real_file,
-                                inp,
-                                oup: &mut compbuf,
-                                archive_recursion_depth,
-                                config: PreprocConfig { cache: None, args },
-                            },
-                            &detection_reason,
-                        )?;
+                        adapter
+                            .adapt(
+                                AdaptInfo {
+                                    line_prefix,
+                                    filepath_hint,
+                                    is_real_file,
+                                    inp,
+                                    oup: &mut compbuf,
+                                    archive_recursion_depth,
+                                    config: PreprocConfig { cache: None, args },
+                                },
+                                &detection_reason,
+                            )
+                            .with_context(|| {
+                                format!(
+                                    "adapting {} via {} failed",
+                                    filepath_hint.to_string_lossy(),
+                                    meta.name
+                                )
+                            })?;
                         let compressed = compbuf
                             .into_inner()
                             .map_err(|_| "could not finish zstd") // can't use with_context here
@@ -138,19 +146,28 @@ pub fn rga_preproc(ai: AdaptInfo) -> Result<()> {
                 )?;
                 Ok(())
             } else {
+                // couldn't open cache
                 debug!("adapting...");
-                adapter.adapt(
-                    AdaptInfo {
-                        line_prefix,
-                        filepath_hint,
-                        is_real_file,
-                        inp,
-                        oup,
-                        archive_recursion_depth,
-                        config: PreprocConfig { cache: None, args },
-                    },
-                    &detection_reason,
-                )?;
+                adapter
+                    .adapt(
+                        AdaptInfo {
+                            line_prefix,
+                            filepath_hint,
+                            is_real_file,
+                            inp,
+                            oup,
+                            archive_recursion_depth,
+                            config: PreprocConfig { cache: None, args },
+                        },
+                        &detection_reason,
+                    )
+                    .with_context(|| {
+                        format!(
+                            "adapting {} via {} without caching failed",
+                            filepath_hint.to_string_lossy(),
+                            meta.name
+                        )
+                    })?;
                 Ok(())
             }
         }

src/preproc_cache.rs

@@ -23,9 +23,9 @@ pub trait PreprocCache {
 fn open_cache_db() -> Result<std::sync::Arc<std::sync::RwLock<rkv::Rkv>>> {
     let app_cache = cachedir::CacheDirConfig::new("rga").get_cache_dir()?;
 
-    let db_arc = rkv::Manager::singleton()
+    rkv::Manager::singleton()
         .write()
-        .expect("could not write db manager")
+        .map_err(|_| format_err!("could not write cache db manager"))?
         .get_or_create(app_cache.as_path(), |p| {
             let mut builder = rkv::Rkv::environment_builder();
             builder
@@ -40,8 +40,7 @@ fn open_cache_db() -> Result<std::sync::Arc<std::sync::RwLock<rkv::Rkv>>> {
                 .set_max_readers(128);
             rkv::Rkv::from_env(p, builder)
         })
-        .expect("could not get/create db");
-    Ok(db_arc)
+        .map_err(|e| format_err!("could not get/create cache db: {}", e))
 }
 
 pub struct LmdbCache {