From 061e9453848bf047430e5abe1c5b8574289b3d87 Mon Sep 17 00:00:00 2001
From: Philippe PITTOLI <karchnu@karchnu.fr>
Date: Mon, 6 May 2024 13:02:14 +0200
Subject: [PATCH] Add cached indexes (index, partition, tag): we are now 500x
 faster.

---
 src/cached.cr         | 18 ++++++++++++++++++
 src/dodb/index.cr     | 40 ++++++++++++++++++++++++++++++++++++++++
 src/dodb/partition.cr | 38 ++++++++++++++++++++++++++++++++++++++
 src/dodb/tags.cr      | 43 +++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 139 insertions(+)

diff --git a/src/cached.cr b/src/cached.cr
index b3a88e7..c4f436b 100644
--- a/src/cached.cr
+++ b/src/cached.cr
@@ -108,4 +108,22 @@ class DODB::CachedDataBase(V) < DODB::Storage(V)
 		super
 		@data = Hash(Int32, V).new
 	end
+
+	def new_index(name : String, &block : Proc(V, String))
+		CachedIndex(V).new(self, @directory_name, name, block).tap do |indexer|
+			@indexers << indexer
+		end
+	end
+
+	def new_partition(name : String, &block : Proc(V, String))
+		CachedPartition(V).new(self, @directory_name, name, block).tap do |table|
+			@indexers << table
+		end
+	end
+
+	def new_tags(name : String, &block : Proc(V, Array(String)))
+		CachedTags(V).new(self, @directory_name, name, block).tap do |tags|
+			@indexers << tags
+		end
+	end
 end
diff --git a/src/dodb/index.cr b/src/dodb/index.cr
index 5c0f31d..6326a57 100644
--- a/src/dodb/index.cr
+++ b/src/dodb/index.cr
@@ -142,3 +142,43 @@ class DODB::Index(V) < DODB::Indexer(V)
 	end
 end
 
+class DODB::CachedIndex(V) < DODB::Index(V)
+	# This hash contains the relation between the index key and the data key.
+	property data = Hash(String, Int32).new
+
+	def check!(key, value, old_value)
+		index_key = key_proc.call value
+
+		# FIXME: Check it’s not pointing to “old_value”, if any, before raising.
+		if data[index_key]?
+			if old_value
+				old_key = key_proc.call old_value
+				return if index_key == old_key
+			end
+
+			raise IndexOverload.new "index '#{@name}' is overloaded for key '#{key}'"
+		end
+	end
+
+	def index(key, value)
+		super(key, value)
+
+		index_key = key_proc.call value
+		return if index_key.is_a? NoIndex
+
+		@data[index_key] = key.to_i
+	end
+
+	def deindex(key, value)
+		super(key, value)
+
+		index_key = key_proc.call value
+		return if index_key.is_a? NoIndex
+
+		@data.delete index_key
+	end
+
+	def get(index : String) : V
+		@storage[@data[index]]
+	end
+end
diff --git a/src/dodb/partition.cr b/src/dodb/partition.cr
index 0060932..6aa817c 100644
--- a/src/dodb/partition.cr
+++ b/src/dodb/partition.cr
@@ -93,3 +93,41 @@ class DODB::Partition(V) < DODB::Indexer(V)
 	end
 end
 
+class DODB::CachedPartition(V) < DODB::Partition(V)
+	# This hash contains the relation between the index key and the data keys.
+	property data = Hash(String, Array(Int32)).new
+
+	def index(key, value)
+		super(key, value)
+		partition = key_proc.call value
+
+		array = if v = @data[partition]?
+			v
+		else
+			Array(Int32).new
+		end
+		array << key.to_i
+
+		@data[partition] = array
+	end
+
+	def deindex(key, value)
+		super(key, value)
+		partition = key_proc.call value
+
+		if v = @data[partition]?
+			v.delete key.to_i
+			@data[partition] = v
+		end
+	end
+
+	def get(partition)
+		r_value = Array(V).new
+
+		@data[partition].each do |data_key|
+			r_value << @storage[data_key]
+		end
+
+		r_value
+	end
+end
diff --git a/src/dodb/tags.cr b/src/dodb/tags.cr
index 1c53386..30f9c5b 100644
--- a/src/dodb/tags.cr
+++ b/src/dodb/tags.cr
@@ -107,3 +107,46 @@ class DODB::Tags(V) < DODB::Indexer(V)
 		"../../../data/#{key}"
 	end
 end
+
+class DODB::CachedTags(V) < DODB::Tags(V)
+	# This hash contains the relation between the index key and the data keys.
+	property data = Hash(String, Array(Int32)).new
+
+	def index(key, value)
+		super(key, value)
+		indices = key_proc.call value
+
+		indices.each do |tag|
+			array = if v = @data[tag]?
+				v
+			else
+				Array(Int32).new
+			end
+			array << key.to_i
+
+			@data[tag] = array
+		end
+	end
+
+	def deindex(key, value)
+		super(key, value)
+		indices = key_proc.call value
+
+		indices.each do |tag|
+			if v = @data[tag]?
+				v.delete key.to_i
+				@data[tag] = v
+			end
+		end
+	end
+
+	def get(tag : String)
+		r_value = Array(V).new
+
+		@data[tag].each do |data_key|
+			r_value << @storage[data_key]
+		end
+
+		r_value
+	end
+end