From 187d2128374307145e41dc52ba6db2c8de081c75 Mon Sep 17 00:00:00 2001
From: Christopher Berner <me@cberner.com>
Date: Sat, 14 Oct 2023 19:15:28 -0700
Subject: [PATCH] Implement Debug for Table and ReadOnlyTable

---
 src/db.rs           | 23 ++++++++++++++----
 src/table.rs        | 59 +++++++++++++++++++++++++++++++++++++++++++++
 src/transactions.rs |  1 +
 3 files changed, 78 insertions(+), 5 deletions(-)

diff --git a/src/db.rs b/src/db.rs
index 96ef9ed3..de8b1226 100644
--- a/src/db.rs
+++ b/src/db.rs
@@ -408,7 +408,12 @@ impl Database {
             })?
         {
             let savepoint_table: ReadOnlyTable<SavepointId, SerializedSavepoint> =
-                ReadOnlyTable::new(savepoint_table_def.get_root(), PageHint::None, mem)?;
+                ReadOnlyTable::new(
+                    "internal savepoint table".to_string(),
+                    savepoint_table_def.get_root(),
+                    PageHint::None,
+                    mem,
+                )?;
             for result in savepoint_table.range::<SavepointId>(..)? {
                 let (_, savepoint_data) = result?;
                 let savepoint = savepoint_data
@@ -443,8 +448,12 @@ impl Database {
             mem.mark_pages_allocated(freed_pages_iter, true)?;
         }
 
-        let freed_table: ReadOnlyTable<FreedTableKey, FreedPageList<'static>> =
-            ReadOnlyTable::new(freed_root, PageHint::None, mem)?;
+        let freed_table: ReadOnlyTable<FreedTableKey, FreedPageList<'static>> = ReadOnlyTable::new(
+            "internal freed table".to_string(),
+            freed_root,
+            PageHint::None,
+            mem,
+        )?;
         let lookup_key = FreedTableKey {
             transaction_id: oldest_unprocessed_free_transaction.0,
             pagination_id: 0,
@@ -557,8 +566,12 @@ impl Database {
         let freed_root = mem.get_freed_root();
         // Allow processing of all transactions, since this is the main freed tree
         Self::mark_freed_tree(freed_root, mem, TransactionId(0))?;
-        let freed_table: ReadOnlyTable<FreedTableKey, FreedPageList<'static>> =
-            ReadOnlyTable::new(freed_root, PageHint::None, mem)?;
+        let freed_table: ReadOnlyTable<FreedTableKey, FreedPageList<'static>> = ReadOnlyTable::new(
+            "internal freed table".to_string(),
+            freed_root,
+            PageHint::None,
+            mem,
+        )?;
         // The persistent savepoints might hold references to older freed trees that are partially processed.
         // Make sure we don't reprocess those frees, as that would result in a double-free
         let oldest_unprocessed_transaction =
diff --git a/src/table.rs b/src/table.rs
index 60505ce9..b5f1abee 100644
--- a/src/table.rs
+++ b/src/table.rs
@@ -7,6 +7,7 @@ use crate::types::{RedbKey, RedbValue, RedbValueMutInPlace};
 use crate::Result;
 use crate::{AccessGuard, StorageError, WriteTransaction};
 use std::borrow::Borrow;
+use std::fmt::{Debug, Formatter};
 use std::ops::RangeBounds;
 use std::sync::{Arc, Mutex};
 
@@ -249,6 +250,55 @@ impl<'db, 'txn, K: RedbKey + 'static, V: RedbValue + 'static> Drop for Table<'db
     }
 }
 
+fn debug_helper<K: RedbKey + 'static, V: RedbValue + 'static>(
+    f: &mut Formatter<'_>,
+    name: &str,
+    len: Result<u64>,
+    first: Result<Option<(AccessGuard<K>, AccessGuard<V>)>>,
+    last: Result<Option<(AccessGuard<K>, AccessGuard<V>)>>,
+) -> std::fmt::Result {
+    write!(f, "Table [ name: \"{}\", ", name)?;
+    if let Ok(len) = len {
+        if len == 0 {
+            write!(f, "No entries")?;
+        } else if len == 1 {
+            if let Ok(first) = first {
+                let (key, value) = first.as_ref().unwrap();
+                write!(f, "One key-value: {:?} = {:?}", key.value(), value.value())?;
+            } else {
+                write!(f, "I/O Error accessing table!")?;
+            }
+        } else {
+            if let Ok(first) = first {
+                let (key, value) = first.as_ref().unwrap();
+                write!(f, "first: {:?} = {:?}, ", key.value(), value.value())?;
+            } else {
+                write!(f, "I/O Error accessing table!")?;
+            }
+            if len > 2 {
+                write!(f, "...{} more entries..., ", len - 2)?;
+            }
+            if let Ok(last) = last {
+                let (key, value) = last.as_ref().unwrap();
+                write!(f, "last: {:?} = {:?}", key.value(), value.value())?;
+            } else {
+                write!(f, "I/O Error accessing table!")?;
+            }
+        }
+    } else {
+        write!(f, "I/O Error accessing table!")?;
+    }
+    write!(f, " ]")?;
+
+    Ok(())
+}
+
+impl<K: RedbKey + 'static, V: RedbValue + 'static> Debug for Table<'_, '_, K, V> {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        debug_helper(f, &self.name, self.len(), self.first(), self.last())
+    }
+}
+
 pub trait ReadableTable<K: RedbKey + 'static, V: RedbValue + 'static>: Sealed {
     /// Returns the value corresponding to the given key
     fn get<'a>(&self, key: impl Borrow<K::SelfType<'a>>) -> Result<Option<AccessGuard<V>>>
@@ -319,16 +369,19 @@ pub trait ReadableTable<K: RedbKey + 'static, V: RedbValue + 'static>: Sealed {
 
 /// A read-only table
 pub struct ReadOnlyTable<'txn, K: RedbKey + 'static, V: RedbValue + 'static> {
+    name: String,
     tree: Btree<'txn, K, V>,
 }
 
 impl<'txn, K: RedbKey + 'static, V: RedbValue + 'static> ReadOnlyTable<'txn, K, V> {
     pub(crate) fn new(
+        name: String,
         root_page: Option<(PageNumber, Checksum)>,
         hint: PageHint,
         mem: &'txn TransactionalMemory,
     ) -> Result<ReadOnlyTable<'txn, K, V>> {
         Ok(ReadOnlyTable {
+            name,
             tree: Btree::new(root_page, hint, mem)?,
         })
     }
@@ -376,6 +429,12 @@ impl<'txn, K: RedbKey + 'static, V: RedbValue + 'static> ReadableTable<K, V>
 
 impl<K: RedbKey, V: RedbValue> Sealed for ReadOnlyTable<'_, K, V> {}
 
+impl<K: RedbKey + 'static, V: RedbValue + 'static> Debug for ReadOnlyTable<'_, K, V> {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        debug_helper(f, &self.name, self.len(), self.first(), self.last())
+    }
+}
+
 pub struct Drain<'a, K: RedbKey + 'static, V: RedbValue + 'static> {
     inner: BtreeDrain<'a, K, V>,
 }
diff --git a/src/transactions.rs b/src/transactions.rs
index e0b6299d..5e50a223 100644
--- a/src/transactions.rs
+++ b/src/transactions.rs
@@ -1150,6 +1150,7 @@ impl<'db> ReadTransaction<'db> {
             .ok_or_else(|| TableError::TableDoesNotExist(definition.name().to_string()))?;
 
         Ok(ReadOnlyTable::new(
+            definition.name().to_string(),
             header.get_root(),
             PageHint::Clean,
             self.mem,