From 7560854370854ffce33667576782b580c7875ac4 Mon Sep 17 00:00:00 2001
From: Heikki Linnakangas <heikki@zenith.tech>
Date: Wed, 16 Mar 2022 19:29:07 +0200
Subject: [PATCH] Rename things in KeyPartition, per Bojan's suggestions.

---
 pageserver/src/keyspace.rs           | 25 +++++++++++++++----------
 pageserver/src/layered_repository.rs | 21 +++++++++++----------
 2 files changed, 26 insertions(+), 20 deletions(-)

diff --git a/pageserver/src/keyspace.rs b/pageserver/src/keyspace.rs
index 274c858338..aeaceb37fc 100644
--- a/pageserver/src/keyspace.rs
+++ b/pageserver/src/keyspace.rs
@@ -8,10 +8,11 @@ pub const TARGET_FILE_SIZE_BYTES: u64 = 128 * 1024 * 1024; // 128 MB
 ///
 /// Represents a set of Keys, in a compact form.
 ///
+#[derive(Clone, Debug)]
 pub struct KeySpace {
     // Contiguous ranges of keys that belong to the key space. In key order, and
     // with no overlap.
-    ranges: Vec<Range<Key>>,
+    pub ranges: Vec<Range<Key>>,
 }
 
 impl KeySpace {
@@ -23,7 +24,7 @@ impl KeySpace {
         // Assume that each value is 8k in size.
         let target_nblocks = (target_size / pg_constants::BLCKSZ as u64) as usize;
 
-        let mut partitions = Vec::new();
+        let mut parts = Vec::new();
         let mut current_part = Vec::new();
         let mut current_part_size: usize = 0;
         for range in &self.ranges {
@@ -31,7 +32,9 @@ impl KeySpace {
             // partition would cause it to be too large, start a new partition.
             let this_size = key_range_size(range) as usize;
             if current_part_size + this_size > target_nblocks && !current_part.is_empty() {
-                partitions.push(current_part);
+                parts.push(KeySpace {
+                    ranges: current_part,
+                });
                 current_part = Vec::new();
                 current_part_size = 0;
             }
@@ -42,7 +45,9 @@ impl KeySpace {
             let mut start = range.start;
             while remain_size > target_nblocks {
                 let next = start.add(target_nblocks as u32);
-                partitions.push(vec![start..next]);
+                parts.push(KeySpace {
+                    ranges: vec![start..next],
+                });
                 start = next;
                 remain_size -= target_nblocks
             }
@@ -52,10 +57,12 @@ impl KeySpace {
 
         // add last partition that wasn't full yet.
         if !current_part.is_empty() {
-            partitions.push(current_part);
+            parts.push(KeySpace {
+                ranges: current_part,
+            });
         }
 
-        KeyPartitioning { partitions }
+        KeyPartitioning { parts }
     }
 }
 
@@ -68,14 +75,12 @@ impl KeySpace {
 ///
 #[derive(Clone, Debug, Default)]
 pub struct KeyPartitioning {
-    pub partitions: Vec<Vec<Range<Key>>>,
+    pub parts: Vec<KeySpace>,
 }
 
 impl KeyPartitioning {
     pub fn new() -> Self {
-        KeyPartitioning {
-            partitions: Vec::new(),
-        }
+        KeyPartitioning { parts: Vec::new() }
     }
 }
 
diff --git a/pageserver/src/layered_repository.rs b/pageserver/src/layered_repository.rs
index 526d0c952f..99671c350a 100644
--- a/pageserver/src/layered_repository.rs
+++ b/pageserver/src/layered_repository.rs
@@ -34,7 +34,7 @@ use std::time::Instant;
 
 use self::metadata::{metadata_path, TimelineMetadata, METADATA_FILE_NAME};
 use crate::config::PageServerConf;
-use crate::keyspace::KeyPartitioning;
+use crate::keyspace::{KeyPartitioning, KeySpace};
 use crate::remote_storage::{schedule_timeline_checkpoint_upload, schedule_timeline_download};
 use crate::repository::{
     GcResult, Repository, RepositoryTimeline, Timeline, TimelineSyncState, TimelineWriter,
@@ -1569,14 +1569,14 @@ impl LayeredTimeline {
             // Make a copy of the partitioning, so that we can release
             // the lock. Otherwise we could block the WAL receiver.
             let lsn = *lsn;
-            let partitions = partitioning.partitions.clone();
+            let parts = partitioning.parts.clone();
             drop(partitioning_guard);
 
             // 2. Create new image layers for partitions that have been modified
             // "enough".
-            for partition in partitions.iter() {
-                if self.time_for_new_image_layer(partition, lsn, 3)? {
-                    self.create_image_layer(partition, lsn)?;
+            for part in parts.iter() {
+                if self.time_for_new_image_layer(part, lsn, 3)? {
+                    self.create_image_layer(part, lsn)?;
                 }
             }
             timer.stop_and_record();
@@ -1604,13 +1604,13 @@ impl LayeredTimeline {
     // Is it time to create a new image layer for the given partition?
     fn time_for_new_image_layer(
         &self,
-        partition: &[Range<Key>],
+        partition: &KeySpace,
         lsn: Lsn,
         threshold: usize,
     ) -> Result<bool> {
         let layers = self.layers.lock().unwrap();
 
-        for part_range in partition {
+        for part_range in &partition.ranges {
             let image_coverage = layers.image_coverage(part_range, lsn)?;
             for (img_range, last_img) in image_coverage {
                 let img_lsn = if let Some(ref last_img) = last_img {
@@ -1634,12 +1634,13 @@ impl LayeredTimeline {
         Ok(false)
     }
 
-    fn create_image_layer(&self, partition: &[Range<Key>], lsn: Lsn) -> Result<()> {
-        let img_range = partition.first().unwrap().start..partition.last().unwrap().end;
+    fn create_image_layer(&self, partition: &KeySpace, lsn: Lsn) -> Result<()> {
+        let img_range =
+            partition.ranges.first().unwrap().start..partition.ranges.last().unwrap().end;
         let mut image_layer_writer =
             ImageLayerWriter::new(self.conf, self.timelineid, self.tenantid, &img_range, lsn)?;
 
-        for range in partition {
+        for range in &partition.ranges {
             let mut key = range.start;
             while key < range.end {
                 let img = self.get(key, lsn)?;