Simpler chunking :)

app/models/ci/build.rb

@@ -25,6 +25,8 @@ module Ci
     has_one :job_artifacts_metadata, -> { where(file_type: Ci::JobArtifact.file_types[:metadata]) }, class_name: 'Ci::JobArtifact', inverse_of: :job, foreign_key: :job_id
     has_one :job_artifacts_trace, -> { where(file_type: Ci::JobArtifact.file_types[:trace]) }, class_name: 'Ci::JobArtifact', inverse_of: :job, foreign_key: :job_id
 
+    has_many :chunks, class_name: 'Ci::JobTraceChunk', foreign_key: :job_id, dependent: :destroy # rubocop:disable Cop/ActiveRecordDependent
+
     has_one :metadata, class_name: 'Ci::BuildMetadata'
     delegate :timeout, to: :metadata, prefix: true, allow_nil: true
 

app/models/ci/job_trace_chunk.rb

@@ -3,5 +3,112 @@ module Ci
     extend Gitlab::Ci::Model
 
     belongs_to :job, class_name: "Ci::Build", foreign_key: :job_id
+
+    after_destroy :redis_delete_data, if: :redis?
+
+    default_value_for :data_store, :redis
+
+    CHUNK_SIZE = 8
+    CHUNK_REDIS_TTL = 1.month
+
+    enum data_store: {
+      redis: 1,
+      db: 2,
+    }
+
+    def data
+      case 
+      when redis?
+        redis_data
+      when db?
+        raw_data
+      else
+        raise 'Unsupported data store'
+      end
+    end
+
+    def set_data(value)
+      raise 'too much data' if value.length > CHUNK_SIZE
+
+      case
+      when redis?
+        redis_set_data(value)
+      when db?
+        self.raw_data = value
+      else
+        raise 'Unsupported data store'
+      end
+
+      save if changed?
+      schedule_to_db if fullfilled?
+    end
+
+    def truncate(offset = 0)
+      self.append("", offset)
+    end
+
+    def append(new_data, offset)
+      current_data = self.data || ""
+      raise 'Outside of if data' if offset > current_data.bytesize
+
+      self.set_data(current_data.byteslice(0, offset) + new_data)
+    end
+
+    def size
+      data&.bytesize.to_i
+    end
+
+    def start_offset
+      chunk_index * CHUNK_SIZE
+    end
+
+    def end_offset
+      start_offset + size
+    end
+
+    def range
+      (start_offset...end_offset)
+    end
+
+    def use_database!
+      return if db?
+
+      self.update!(raw_data: data, data_store: :db)
+      redis_delete_data
+    end
+
+    private
+
+    def schedule_to_db
+      return if db?
+
+      self.use_database!
+    end
+
+    def fullfilled?
+      size == CHUNK_SIZE
+    end
+
+    def redis_data
+      Gitlab::Redis::SharedState.with do |redis|
+        redis.get(redis_key)
+      end
+    end
+
+    def redis_set_data(data)
+      Gitlab::Redis::SharedState.with do |redis|
+        redis.set(redis_key, data, ex: CHUNK_REDIS_TTL)
+      end
+    end
+
+    def redis_delete_data
+      Gitlab::Redis::SharedState.with do |redis|
+        redis.del(redis_key)
+      end
+    end
+
+    def redis_key
+      "gitlab:ci:trace:#{job_id}:chunks:#{chunk_index}"
+    end
   end
 end

db/migrate/20180326202229_create_ci_job_trace_chunks.rb

@@ -7,7 +7,8 @@ class CreateCiJobTraceChunks < ActiveRecord::Migration
     create_table :ci_job_trace_chunks do |t|
       t.integer :job_id, null: false
       t.integer :chunk_index, null: false
-      t.text :data
+      t.integer :data_store, null: false
+      t.text :raw_data
 
       t.foreign_key :ci_builds, column: :job_id, on_delete: :cascade
       t.index [:chunk_index, :job_id], unique: true

db/schema.rb

@@ -373,7 +373,8 @@ ActiveRecord::Schema.define(version: 20180327101207) do
   create_table "ci_job_trace_chunks", force: :cascade do |t|
     t.integer "job_id", null: false
     t.integer "chunk_index", null: false
-    t.text "data"
+    t.integer "data_store", null: false
+    t.text "raw_data"
   end
 
   add_index "ci_job_trace_chunks", ["chunk_index", "job_id"], name: "index_ci_job_trace_chunks_on_chunk_index_and_job_id", unique: true, using: :btree

lib/gitlab/ci/trace.rb

@@ -54,15 +54,15 @@ module Gitlab
       end
 
       def exist?
-        trace_artifact&.exists? || ChunkedFile::LiveTrace.exist?(job.id) || current_path.present? || old_trace.present?
+        trace_artifact&.exists? || job.chunks.any? || current_path.present? || old_trace.present?
       end
 
       def read
         stream = Gitlab::Ci::Trace::Stream.new do
           if trace_artifact
             trace_artifact.open
-          elsif ChunkedFile::LiveTrace.exist?(job.id)
-            ChunkedFile::LiveTrace.new(job.id, nil, "rb")
+          elsif job.chunks.any?
+            Gitlab::Ci::Trace::ChunkedIO.new(job)
           elsif current_path
             File.open(current_path, "rb")
           elsif old_trace
@@ -77,12 +77,10 @@ module Gitlab
 
       def write
         stream = Gitlab::Ci::Trace::Stream.new do
-          if Feature.enabled?('ci_enable_live_trace')
-            if current_path
-              current_path
-            else
-              ChunkedFile::LiveTrace.new(job.id, nil, "a+b")
-            end
+          if current_path
+            current_path
+          elsif Feature.enabled?('ci_enable_live_trace')
+            Gitlab::Ci::Trace::ChunkedIO.new(job)
           else
             File.open(ensure_path, "a+b")
           end
@@ -102,6 +100,7 @@ module Gitlab
           FileUtils.rm(trace_path, force: true)
         end
 
+        job.chunks.destroy_all
         job.erase_old_trace!
       end
 
@@ -109,13 +108,10 @@ module Gitlab
         raise ArchiveError, 'Already archived' if trace_artifact
         raise ArchiveError, 'Job is not finished yet' unless job.complete?
 
-        if ChunkedFile::LiveTrace.exist?(job.id)
-          ChunkedFile::LiveTrace.new(job.id, nil, 'a+b') do |live_trace_stream|
-            StringIO.new(live_trace_stream.read, 'rb').tap do |stream|
-              archive_stream!(stream)
-            end
-
-            live_trace_stream.delete
+        if job.chunks.any?
+          Gitlab::Ci::Trace::ChunkedIO.new(job) do |stream|
+            archive_stream!(stream)
+            stream.destroy!
           end
         elsif current_path
           File.open(current_path) do |stream|

lib/gitlab/ci/trace/chunked_io.rb

@@ -0,0 +1,216 @@
+##
+# This class is compatible with IO class (https://ruby-doc.org/core-2.3.1/IO.html)
+# source: https://gitlab.com/snippets/1685610
+module Gitlab
+  module Ci
+    class Trace
+      class ChunkedIO
+        CHUNK_SIZE = ::Ci::JobTraceChunk::CHUNK_SIZE
+
+        FailedToGetChunkError = Class.new(StandardError)
+
+        attr_reader :job
+        attr_reader :tell, :size
+        attr_reader :chunk, :chunk_range
+
+        alias_method :pos, :tell
+
+        def initialize(job)
+          @job = job
+          @chunks_cache = []
+          @tell = 0
+          @size = job_chunks.last.try(&:end_offset).to_i
+        end
+
+        def close
+          # no-op
+        end
+
+        def binmode
+          # no-op
+        end
+
+        def binmode?
+          true
+        end
+
+        def path
+          nil
+        end
+
+        def url
+          nil
+        end
+
+        def seek(pos, where = IO::SEEK_SET)
+          new_pos =
+            case where
+            when IO::SEEK_END
+              size + pos
+            when IO::SEEK_SET
+              pos
+            when IO::SEEK_CUR
+              tell + pos
+            else
+              -1
+            end
+
+          raise 'new position is outside of file' if new_pos < 0 || new_pos > size
+
+          @tell = new_pos
+        end
+
+        def eof?
+          tell == size
+        end
+
+        def each_line
+          until eof?
+            line = readline
+            break if line.nil?
+
+            yield(line)
+          end
+        end
+
+        def read(length = nil)
+          out = ""
+
+          until eof? || (length && out.length >= length)
+            data = chunk_slice_from_offset
+            break if data.empty?
+
+            out << data
+            @tell += data.bytesize
+          end
+
+          out = out[0, length] if length && out.length > length
+
+          out
+        end
+
+        def readline
+          out = ""
+
+          until eof?
+            data = chunk_slice_from_offset
+            new_line = data.index("\n")
+
+            if !new_line.nil?
+              out << data[0..new_line]
+              @tell += new_line + 1
+              break
+            else
+              out << data
+              @tell += data.bytesize
+            end
+          end
+
+          out
+        end
+
+        def write(data)
+          start_pos = @tell
+
+          while @tell < start_pos + data.bytesize
+            # get slice from current offset till the end where it falls into chunk
+            chunk_bytes = CHUNK_SIZE - chunk_offset
+            chunk_data = data.byteslice(@tell - start_pos, chunk_bytes)
+
+            # append data to chunk, overwriting from that point
+            ensure_chunk.append(chunk_data, chunk_offset)
+
+            # move offsets within buffer
+            @tell += chunk_bytes
+            @size = [@size, @tell].max
+          end
+        end
+
+        def truncate(offset)
+          raise 'Outside of file' if offset > size
+
+          @tell = offset
+          @size = offset
+          invalidate_chunk_cache
+
+          # remove all next chunks
+          job_chunks.where('chunk_index > ?', chunk_index).destroy_all
+
+          # truncate current chunk
+          current_chunk.truncate(chunk_offset) if chunk_offset != 0
+        end
+
+        def flush
+          # no-op
+        end
+
+        def present?
+          true
+        end
+
+        def destroy!
+          job_chunks.destroy_all
+          invalidate_chunk_cache
+        end
+
+        private
+
+        ##
+        # The below methods are not implemented in IO class
+        #
+        def in_range?
+          @chunk_range&.include?(tell)
+        end
+
+        def chunk_slice_from_offset
+          unless in_range?
+            current_chunk.tap do |chunk|
+              raise FailedToGetChunkError unless chunk
+
+              @chunk = chunk.data.force_encoding(Encoding::BINARY)
+              @chunk_range = chunk.range
+            end
+          end
+
+          @chunk.byteslice(chunk_offset, CHUNK_SIZE)
+        end
+
+        def chunk_offset
+          tell % CHUNK_SIZE
+        end
+
+        def chunk_index
+          tell / CHUNK_SIZE
+        end
+
+        def chunk_start
+          chunk_index * CHUNK_SIZE
+        end
+
+        def chunk_end
+          [chunk_start + CHUNK_SIZE, size].min
+        end
+
+        def invalidate_chunk_cache
+          @chunks_cache = []
+        end
+
+        def current_chunk
+          @chunks_cache[chunk_index] ||= job_chunks.find_by(chunk_index: chunk_index)
+        end
+
+        def build_chunk
+          @chunks_cache[chunk_index] = Ci::JobTraceChunk.new(job: job, chunk_index: chunk_index)
+        end
+
+        def ensure_chunk
+          current_chunk || build_chunk
+        end
+
+        def job_chunks
+          Ci::JobTraceChunk.where(job: job)
+        end
+      end
+    end
+  end
+end

lib/gitlab/ci/trace/http_io.rb

@@ -161,7 +161,7 @@ module Gitlab
             @chunk_range ||= (chunk_start...(chunk_start + @chunk.length))
           end
 
-          @chunk[chunk_offset..BUFFER_SIZE]
+          @chunk.byteslice(chunk_offset, BUFFER_SIZE)
         end
 
         def request

lib/gitlab/ci/trace/stream.rb

@@ -40,8 +40,9 @@ module Gitlab
         end
 
         def set(data)
-          truncate(0)
+          stream.seek(0, IO::SEEK_SET)
           stream.write(data)
+          stream.truncate(data.bytesize)
           stream.flush()
         end