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*: Clean up (pingcap#1928)
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* ddl: remove useless code, add and update comments
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@zimulala
zimulala authored Nov 3, 2016
1 parent c74c4f8 commit b4e3e58
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Showing 9 changed files with 208 additions and 221 deletions.
6 changes: 3 additions & 3 deletions ddl/bg_worker.go
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Original file line number Diff line number Diff line change
Expand Up @@ -41,7 +41,7 @@ func (d *ddl) handleBgJobQueue() error {
return errors.Trace(err)
}

// get the first background job and run
// Get the first background job and run it.
job, err = d.getFirstBgJob(t)
if err != nil {
return errors.Trace(err)
Expand Down Expand Up @@ -155,8 +155,8 @@ func (d *ddl) finishBgJob(t *meta.Meta, job *model.Job) error {
func (d *ddl) onBackgroundWorker() {
defer d.wait.Done()

// we use 4 * lease time to check owner's timeout, so here, we will update owner's status
// every 2 * lease time, if lease is 0, we will use default 10s.
// We use 4 * lease time to check owner's timeout, so here, we will update owner's status
// every 2 * lease time. If lease is 0, we will use default 10s.
checkTime := chooseLeaseTime(2*d.lease, 10*time.Second)

ticker := time.NewTicker(checkTime)
Expand Down
53 changes: 22 additions & 31 deletions ddl/column.go
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Original file line number Diff line number Diff line change
Expand Up @@ -46,7 +46,7 @@ func (d *ddl) adjustColumnOffset(columns []*model.ColumnInfo, indices []*model.I
columns[offset].Offset = len(columns) - 1
}

// TODO: index can't cover the add/remove column with offset now, we may check this later.
// TODO: Index can't cover the add/remove column with offset now, we may check this later.

// Update index column offset info.
for _, idx := range indices {
Expand All @@ -59,7 +59,7 @@ func (d *ddl) adjustColumnOffset(columns []*model.ColumnInfo, indices []*model.I
}
}

func (d *ddl) addColumn(tblInfo *model.TableInfo, colInfo *model.ColumnInfo, pos *ast.ColumnPosition) (*model.ColumnInfo, int, error) {
func (d *ddl) createColumnInfo(tblInfo *model.TableInfo, colInfo *model.ColumnInfo, pos *ast.ColumnPosition) (*model.ColumnInfo, int, error) {
// Check column name duplicate.
cols := tblInfo.Columns
position := len(cols)
Expand Down Expand Up @@ -111,17 +111,16 @@ func (d *ddl) onAddColumn(t *meta.Meta, job *model.Job) error {
columnInfo := findCol(tblInfo.Columns, col.Name.L)
if columnInfo != nil {
if columnInfo.State == model.StatePublic {
// we already have a column with same column name
// We already have a column with the same column name.
job.State = model.JobCancelled
return infoschema.ErrColumnExists.Gen("ADD COLUMN: column already exist %s", col.Name.L)
}
} else {
columnInfo, offset, err = d.addColumn(tblInfo, col, pos)
columnInfo, offset, err = d.createColumnInfo(tblInfo, col, pos)
if err != nil {
job.State = model.JobCancelled
return errors.Trace(err)
}

// Set offset arg to job.
if offset != 0 {
job.Args = []interface{}{columnInfo, pos, offset}
Expand All @@ -139,27 +138,24 @@ func (d *ddl) onAddColumn(t *meta.Meta, job *model.Job) error {
job.SchemaState = model.StateDeleteOnly
columnInfo.State = model.StateDeleteOnly
err = t.UpdateTable(schemaID, tblInfo)
return errors.Trace(err)
case model.StateDeleteOnly:
// delete only -> write only
job.SchemaState = model.StateWriteOnly
columnInfo.State = model.StateWriteOnly
err = t.UpdateTable(schemaID, tblInfo)
return errors.Trace(err)
case model.StateWriteOnly:
// write only -> reorganization
job.SchemaState = model.StateWriteReorganization
columnInfo.State = model.StateWriteReorganization
// initialize SnapshotVer to 0 for later reorganization check.
// Initialize SnapshotVer to 0 for later reorganization check.
job.SnapshotVer = 0
err = t.UpdateTable(schemaID, tblInfo)
return errors.Trace(err)
case model.StateWriteReorganization:
// reorganization -> public
// get the current version for reorganization if we don't have
// Get the current version for reorganization if we don't have it.
reorgInfo, err := d.getReorgInfo(t, job)
if err != nil || reorgInfo.first {
// if we run reorg firstly, we should update the job snapshot version
// If we run reorg firstly, we should update the job snapshot version
// and then run the reorg next time.
return errors.Trace(err)
}
Expand All @@ -173,7 +169,8 @@ func (d *ddl) onAddColumn(t *meta.Meta, job *model.Job) error {
return d.addTableColumn(tbl, columnInfo, reorgInfo, job)
})
if terror.ErrorEqual(err, errWaitReorgTimeout) {
// if timeout, we should return, check for the owner and re-wait job done.
// If the timeout happens, we should return.
// Then check for the owner and re-wait job to finish.
return nil
}
if err != nil {
Expand All @@ -183,21 +180,20 @@ func (d *ddl) onAddColumn(t *meta.Meta, job *model.Job) error {

// Adjust column offset.
d.adjustColumnOffset(tblInfo.Columns, tblInfo.Indices, offset, true)

columnInfo.State = model.StatePublic

if err = t.UpdateTable(schemaID, tblInfo); err != nil {
return errors.Trace(err)
}

// finish this job
// Finish this job.
job.SchemaState = model.StatePublic
job.State = model.JobDone
addTableHistoryInfo(job, ver, tblInfo)
return nil
default:
return ErrInvalidColumnState.Gen("invalid column state %v", columnInfo.State)
err = ErrInvalidColumnState.Gen("invalid column state %v", columnInfo.State)
}

return errors.Trace(err)
}

func (d *ddl) onDropColumn(t *meta.Meta, job *model.Job) error {
Expand Down Expand Up @@ -226,8 +222,8 @@ func (d *ddl) onDropColumn(t *meta.Meta, job *model.Job) error {
colName, tblInfo.Name)
}

// we don't support drop column with index covered now.
// we must drop the index first, then drop the column.
// We don't support dropping column with index covered now.
// We must drop the index first, then drop the column.
for _, indexInfo := range tblInfo.Indices {
for _, col := range indexInfo.Columns {
if col.Name.L == colName.L {
Expand All @@ -248,36 +244,31 @@ func (d *ddl) onDropColumn(t *meta.Meta, job *model.Job) error {
// public -> write only
job.SchemaState = model.StateWriteOnly
colInfo.State = model.StateWriteOnly

// set this column's offset to the last and reset all following columns' offset
// Set this column's offset to the last and reset all following columns' offsets.
d.adjustColumnOffset(tblInfo.Columns, tblInfo.Indices, colInfo.Offset, false)

err = t.UpdateTable(schemaID, tblInfo)
return errors.Trace(err)
case model.StateWriteOnly:
// write only -> delete only
job.SchemaState = model.StateDeleteOnly
colInfo.State = model.StateDeleteOnly
err = t.UpdateTable(schemaID, tblInfo)
return errors.Trace(err)
case model.StateDeleteOnly:
// delete only -> reorganization
job.SchemaState = model.StateDeleteReorganization
colInfo.State = model.StateDeleteReorganization
// initialize SnapshotVer to 0 for later reorganization check.
// Initialize SnapshotVer to 0 for later reorganization check.
job.SnapshotVer = 0
err = t.UpdateTable(schemaID, tblInfo)
return errors.Trace(err)
case model.StateDeleteReorganization:
// reorganization -> absent
reorgInfo, err := d.getReorgInfo(t, job)
if err != nil || reorgInfo.first {
// if we run reorg firstly, we should update the job snapshot version
// If we run reorg firstly, we should update the job snapshot version
// and then run the reorg next time.
return errors.Trace(err)
}

// all reorganization jobs done, drop this column
// All reorganization jobs are done, drop this column.
newColumns := make([]*model.ColumnInfo, 0, len(tblInfo.Columns))
for _, col := range tblInfo.Columns {
if col.Name.L != colName.L {
Expand All @@ -289,14 +280,14 @@ func (d *ddl) onDropColumn(t *meta.Meta, job *model.Job) error {
return errors.Trace(err)
}

// finish this job
// Finish this job.
job.SchemaState = model.StateNone
job.State = model.JobDone
addTableHistoryInfo(job, ver, tblInfo)
return nil
default:
return ErrInvalidTableState.Gen("invalid table state %v", tblInfo.State)
err = ErrInvalidTableState.Gen("invalid table state %v", tblInfo.State)
}
return errors.Trace(err)
}

// How to backfill column data in reorganization state?
Expand Down
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