Class: Innodb::Page::Index::RecordCursor
- Inherits:
-
Object
- Object
- Innodb::Page::Index::RecordCursor
- Defined in:
- lib/innodb/page/index.rb
Overview
A class for cursoring through records starting from an arbitrary point.
Instance Method Summary collapse
-
#each_record ⇒ Object
Iterate through all records in the cursor.
-
#initialize(page, offset, direction) ⇒ RecordCursor
constructor
A new instance of RecordCursor.
-
#next_record ⇒ Object
Return the next record, and advance the cursor.
-
#prev_record ⇒ Object
Return the previous record, and advance the cursor.
-
#record ⇒ Object
Return the next record in the order defined when the cursor was created.
Constructor Details
#initialize(page, offset, direction) ⇒ RecordCursor
Returns a new instance of RecordCursor.
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# File 'lib/innodb/page/index.rb', line 649 def initialize(page, offset, direction) Innodb::Stats.increment :page_record_cursor_create @initial = true @page = page @direction = direction case offset when :min @record = @page.min_record when :max @record = @page.max_record else # Offset is a byte offset of a record (hopefully). @record = @page.record(offset) end end |
Instance Method Details
#each_record ⇒ Object
Iterate through all records in the cursor.
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# File 'lib/innodb/page/index.rb', line 722 def each_record unless block_given? return enum_for(:each_record) end while rec = record yield rec end end |
#next_record ⇒ Object
Return the next record, and advance the cursor. Return nil when the end of records (supremum) is reached.
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# File 'lib/innodb/page/index.rb', line 668 def next_record Innodb::Stats.increment :page_record_cursor_next_record rec = @page.record(@record.next) # The garbage record list's end is self-linked, so we must check for # both supremum and the current record's offset. if rec == @page.supremum || rec.offset == @record.offset # We've reached the end of the linked list at supremum. nil else @record = rec end end |
#prev_record ⇒ Object
Return the previous record, and advance the cursor. Return nil when the end of records (infimum) is reached.
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# File 'lib/innodb/page/index.rb', line 685 def prev_record Innodb::Stats.increment :page_record_cursor_prev_record unless slot = @page.directory_slot_for_record(@record) raise "Couldn't find slot for record" end unless search_cursor = @page.record_cursor(@page.directory[slot-1]) raise "Couldn't position search cursor" end while rec = search_cursor.record and rec.offset != @record.offset if rec.next == @record.offset if rec == @page.infimum return nil end return @record = rec end end end |
#record ⇒ Object
Return the next record in the order defined when the cursor was created.
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# File 'lib/innodb/page/index.rb', line 707 def record if @initial @initial = false return @record end case @direction when :forward next_record when :backward prev_record end end |