[cache (rust)] Prepare for cache_repair

- Adapt function interfaces for repairing purpose
- Finalize the metadata in the Restorer
- Make the Restorer public

src/bin/cache_restore.rs

@@ -29,6 +29,12 @@ fn main() {
                 .value_name("OVERRIDE_MAPPING_ROOT")
                 .takes_value(true),
         )
+        .arg(
+            Arg::with_name("QUIET")
+                .help("Suppress output messages, return only exit code.")
+                .short("q")
+                .long("quiet"),
+        )
         // options
         .arg(
             Arg::with_name("INPUT")

src/cache/dump.rs

@@ -218,15 +218,12 @@ fn mk_context(opts: &CacheDumpOptions) -> anyhow::Result<Context> {
     Ok(Context { engine })
 }
 
-fn dump_metadata(
-    ctx: &Context,
-    w: &mut dyn Write,
+pub fn dump_metadata(
+    engine: Arc<dyn IoEngine + Send + Sync>,
+    out: &mut dyn MetadataVisitor,
     sb: &Superblock,
     _repair: bool,
 ) -> anyhow::Result<()> {
-    let engine = &ctx.engine;
-
-    let mut out = xml::XmlWriter::new(w);
     let xml_sb = ir::Superblock {
         uuid: "".to_string(),
         block_size: sb.data_block_size,
@@ -240,7 +237,7 @@ fn dump_metadata(
     let valid_mappings = match sb.version {
         1 => {
             let w = ArrayWalker::new(engine.clone(), false);
-            let mut emitter = format1::MappingEmitter::new(sb.cache_blocks as usize, &mut out);
+            let mut emitter = format1::MappingEmitter::new(sb.cache_blocks as usize, out);
             w.walk(&mut emitter, sb.mapping_root)?;
             emitter.get_valid()
         }
@@ -263,7 +260,7 @@ fn dump_metadata(
 
             let w = ArrayWalker::new(engine.clone(), false);
             let mut emitter =
-                format2::MappingEmitter::new(sb.cache_blocks as usize, dirty_bits, &mut out);
+                format2::MappingEmitter::new(sb.cache_blocks as usize, dirty_bits, out);
             w.walk(&mut emitter, sb.mapping_root)?;
             emitter.get_valid()
         }
@@ -276,7 +273,7 @@ fn dump_metadata(
     out.hints_b()?;
     {
         let w = ArrayWalker::new(engine.clone(), false);
-        let mut emitter = HintEmitter::new(&mut out, valid_mappings);
+        let mut emitter = HintEmitter::new(out, valid_mappings);
         w.walk(&mut emitter, sb.hint_root)?;
     }
     out.hints_e()?;
@@ -289,17 +286,17 @@ fn dump_metadata(
 
 pub fn dump(opts: CacheDumpOptions) -> anyhow::Result<()> {
     let ctx = mk_context(&opts)?;
-    let engine = &ctx.engine;
-    let sb = read_superblock(engine.as_ref(), SUPERBLOCK_LOCATION)?;
+    let sb = read_superblock(ctx.engine.as_ref(), SUPERBLOCK_LOCATION)?;
 
-    let mut writer: Box<dyn Write>;
+    let writer: Box<dyn Write>;
     if opts.output.is_some() {
         writer = Box::new(BufWriter::new(File::create(opts.output.unwrap())?));
     } else {
         writer = Box::new(BufWriter::new(std::io::stdout()));
     }
+    let mut out = xml::XmlWriter::new(writer);
 
-    dump_metadata(&ctx, &mut writer, &sb, opts.repair)
+    dump_metadata(ctx.engine.clone(), &mut out, &sb, opts.repair)
 }
 
 //------------------------------------------

src/cache/restore.rs

@@ -1,4 +1,4 @@
-use anyhow::{anyhow, Result};
+use anyhow::Result;
 
 use std::convert::TryInto;
 use std::fs::OpenOptions;
@@ -56,15 +56,7 @@ fn mk_context(opts: &CacheRestoreOptions) -> anyhow::Result<Context> {
 
 //------------------------------------------
 
-struct RestoreResult {
-    sb: ir::Superblock,
-    mapping_root: u64,
-    dirty_root: Option<u64>,
-    hint_root: u64,
-    discard_root: u64,
-}
-
-struct Restorer<'a> {
+pub struct Restorer<'a> {
     write_batcher: &'a mut WriteBatcher,
     sb: Option<ir::Superblock>,
     mapping_builder: Option<ArrayBuilder<Mapping>>,
@@ -78,7 +70,7 @@ struct Restorer<'a> {
 }
 
 impl<'a> Restorer<'a> {
-    fn new(w: &'a mut WriteBatcher) -> Restorer<'a> {
+    pub fn new(w: &'a mut WriteBatcher) -> Restorer<'a> {
         Restorer {
             write_batcher: w,
             sb: None,
@@ -93,22 +85,42 @@ impl<'a> Restorer<'a> {
         }
     }
 
-    fn get_result(self) -> Result<RestoreResult> {
-        self.write_batcher.flush()?;
+    fn finalize(&mut self) -> Result<()> {
+        // build metadata space map
+        let metadata_sm_root = build_metadata_sm(self.write_batcher)?;
 
-        if self.sb.is_none() || self.discard_root.is_none() {
-            return Err(anyhow!("No superblock found in xml file"));
-        }
-        if self.mapping_root.is_none() || self.hint_root.is_none() {
-            return Err(anyhow!("No mappings or hints sections in xml file"));
-        }
-        Ok(RestoreResult {
-            sb: self.sb.unwrap(),
-            mapping_root: self.mapping_root.unwrap(),
-            dirty_root: self.dirty_root,
-            hint_root: self.hint_root.unwrap(),
-            discard_root: self.discard_root.unwrap(),
-        })
+        let sb = self.sb.as_ref().unwrap();
+        let mapping_root = self.mapping_root.as_ref().unwrap();
+        let hint_root = self.hint_root.as_ref().unwrap();
+        let discard_root = self.discard_root.as_ref().unwrap();
+        let sb = Superblock {
+            flags: SuperblockFlags {
+                clean_shutdown: true,
+                needs_check: false,
+            },
+            block: SUPERBLOCK_LOCATION,
+            version: 2,
+            policy_name: sb.policy.as_bytes().to_vec(),
+            policy_version: vec![2, 0, 0],
+            policy_hint_size: sb.hint_width,
+            metadata_sm_root,
+            mapping_root: *mapping_root,
+            dirty_root: self.dirty_root, // dirty_root is optional
+            hint_root: *hint_root,
+            discard_root: *discard_root,
+            discard_block_size: 0,
+            discard_nr_blocks: 0,
+            data_block_size: sb.block_size,
+            cache_blocks: sb.nr_cache_blocks,
+            compat_flags: 0,
+            compat_ro_flags: 0,
+            incompat_flags: 0,
+            read_hits: 0,
+            read_misses: 9,
+            write_hits: 0,
+            write_misses: 0,
+        };
+        write_superblock(self.write_batcher.engine.as_ref(), SUPERBLOCK_LOCATION, &sb)
     }
 }
 
@@ -127,6 +139,7 @@ impl<'a> MetadataVisitor for Restorer<'a> {
     }
 
     fn superblock_e(&mut self) -> Result<Visit> {
+        self.finalize()?;
         Ok(Visit::Continue)
     }
 
@@ -252,39 +265,6 @@ pub fn restore(opts: CacheRestoreOptions) -> Result<()> {
     // build cache mappings
     let mut restorer = Restorer::new(&mut w);
     xml::read(input, &mut restorer)?;
-    let result = restorer.get_result()?;
-
-    // build metadata space map
-    let metadata_sm_root = build_metadata_sm(&mut w)?;
-
-    let sb = Superblock {
-        flags: SuperblockFlags {
-            clean_shutdown: true,
-            needs_check: false,
-        },
-        block: SUPERBLOCK_LOCATION,
-        version: 2,
-        policy_name: result.sb.policy.as_bytes().to_vec(),
-        policy_version: vec![2, 0, 0],
-        policy_hint_size: result.sb.hint_width,
-        metadata_sm_root,
-        mapping_root: result.mapping_root,
-        dirty_root: result.dirty_root,
-        hint_root: result.hint_root,
-        discard_root: result.discard_root,
-        discard_block_size: 0,
-        discard_nr_blocks: 0,
-        data_block_size: result.sb.block_size,
-        cache_blocks: result.sb.nr_cache_blocks,
-        compat_flags: 0,
-        compat_ro_flags: 0,
-        incompat_flags: 0,
-        read_hits: 0,
-        read_misses: 9,
-        write_hits: 0,
-        write_misses: 0,
-    };
-    write_superblock(ctx.engine.as_ref(), SUPERBLOCK_LOCATION, &sb)?;
 
     Ok(())
 }