pagectl: add dump layer local (#12245)

## Problem
In our environment, we don't always have access to the pagectl tool on
the pageserver. We have to download the page files to local env to
introspect them. Hence, it'll be useful to be able to parse the local
files using `pagectl`.

## Summary of changes
* Add `dump-layer-local` to `pagectl` that takes a local path as
argument and returns the layer content:
```
cargo  run -p pagectl layer dump-layer-local ~/Desktop/000000067F000040490002800000FFFFFFFF-030000000000000000000000000000000002__00003E7A53EDE611-00003E7AF27BFD19-v1-00000001
```

* Bonus: Fix a bug in `pageserver/ctl/src/draw_timeline_dir.rs` in which
we don't filter out temporary files.

pageserver/ctl/src/draw_timeline_dir.rs

@@ -20,7 +20,7 @@
 //!
 //! # local timeline dir
 //! ls test_output/test_pgbench\[neon-45-684\]/repo/tenants/$TENANT/timelines/$TIMELINE | \
-//!     grep "__" | cargo run --release --bin pagectl draw-timeline-dir > out.svg
+//!     grep "__" | cargo run --release --bin pagectl draw-timeline > out.svg
 //!
 //! # Layer map dump from `/v1/tenant/$TENANT/timeline/$TIMELINE/layer`
 //! (jq -r '.historic_layers[] | .layer_file_name' | cargo  run -p pagectl draw-timeline) < layer-map.json > out.svg
@@ -81,7 +81,11 @@ fn build_coordinate_compression_map<T: Ord + Copy>(coords: Vec<T>) -> BTreeMap<T
 fn parse_filename(name: &str) -> (Range<Key>, Range<Lsn>) {
     let split: Vec<&str> = name.split("__").collect();
     let keys: Vec<&str> = split[0].split('-').collect();
-    let mut lsns: Vec<&str> = split[1].split('-').collect();
+
+    // Remove the temporary file extension, e.g., remove the `.d20a.___temp` part from the following filename:
+    // 000000067F000040490000404A00441B0000-000000067F000040490000404A00441B4000__000043483A34CE00.d20a.___temp
+    let lsns = split[1].split('.').collect::<Vec<&str>>()[0];
+    let mut lsns: Vec<&str> = lsns.split('-').collect();
 
     // The current format of the layer file name: 000000067F0000000400000B150100000000-000000067F0000000400000D350100000000__00000000014B7AC8-v1-00000001
 

pageserver/ctl/src/layers.rs

@@ -13,7 +13,7 @@ use pageserver::{page_cache, virtual_file};
 use pageserver_api::key::Key;
 use utils::id::{TenantId, TimelineId};
 
-use crate::layer_map_analyzer::parse_filename;
+use crate::layer_map_analyzer::{LayerFile, parse_filename};
 
 #[derive(Subcommand)]
 pub(crate) enum LayerCmd {
@@ -38,6 +38,8 @@ pub(crate) enum LayerCmd {
         /// The id from list-layer command
         id: usize,
     },
+    /// Dump all information of a layer file locally
+    DumpLayerLocal { path: PathBuf },
     RewriteSummary {
         layer_file_path: Utf8PathBuf,
         #[clap(long)]
@@ -131,15 +133,7 @@ pub(crate) async fn main(cmd: &LayerCmd) -> Result<()> {
             }
 
             for (idx, layer_file) in to_print {
-                println!(
-                    "[{:3}]  key:{}-{}\n       lsn:{}-{}\n       delta:{}",
-                    idx,
-                    layer_file.key_range.start,
-                    layer_file.key_range.end,
-                    layer_file.lsn_range.start,
-                    layer_file.lsn_range.end,
-                    layer_file.is_delta,
-                );
+                print_layer_file(idx, &layer_file);
             }
             Ok(())
         }
@@ -159,16 +153,7 @@ pub(crate) async fn main(cmd: &LayerCmd) -> Result<()> {
                 let layer = layer?;
                 if let Ok(layer_file) = parse_filename(&layer.file_name().into_string().unwrap()) {
                     if *id == idx {
-                        // TODO(chi): dedup code
-                        println!(
-                            "[{:3}]  key:{}-{}\n       lsn:{}-{}\n       delta:{}",
-                            idx,
-                            layer_file.key_range.start,
-                            layer_file.key_range.end,
-                            layer_file.lsn_range.start,
-                            layer_file.lsn_range.end,
-                            layer_file.is_delta,
-                        );
+                        print_layer_file(idx, &layer_file);
 
                         if layer_file.is_delta {
                             read_delta_file(layer.path(), &ctx).await?;
@@ -183,6 +168,18 @@ pub(crate) async fn main(cmd: &LayerCmd) -> Result<()> {
             }
             Ok(())
         }
+        LayerCmd::DumpLayerLocal { path } => {
+            if let Ok(layer_file) = parse_filename(path.file_name().unwrap().to_str().unwrap()) {
+                print_layer_file(0, &layer_file);
+
+                if layer_file.is_delta {
+                    read_delta_file(path, &ctx).await?;
+                } else {
+                    read_image_file(path, &ctx).await?;
+                }
+            }
+            Ok(())
+        }
         LayerCmd::RewriteSummary {
             layer_file_path,
             new_tenant_id,
@@ -247,3 +244,15 @@ pub(crate) async fn main(cmd: &LayerCmd) -> Result<()> {
         }
     }
 }
+
+fn print_layer_file(idx: usize, layer_file: &LayerFile) {
+    println!(
+        "[{:3}]  key:{}-{}\n       lsn:{}-{}\n       delta:{}",
+        idx,
+        layer_file.key_range.start,
+        layer_file.key_range.end,
+        layer_file.lsn_range.start,
+        layer_file.lsn_range.end,
+        layer_file.is_delta,
+    );
+}