github.com/hasnat/dolt/go@v0.0.0-20210628190320-9eb5d843fbb7/libraries/utils/pipeline/local_storage.go (about)

     1  // Copyright 2020 Dolthub, Inc.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package pipeline
    16  
    17  import "context"
    18  
    19  const localStorageKey = "ls"
    20  
    21  // TODO: get rid of this
    22  // LocalStorage provides routine local storage on go routines spawned by a pipeline
    23  type LocalStorage map[int]interface{}
    24  
    25  // Get retrieves an item from localStorage
    26  func (ls LocalStorage) Get(id int) (interface{}, bool) {
    27  	val, ok := ls[id]
    28  	return val, ok
    29  }
    30  
    31  // Put stores an item in local storage
    32  func (ls LocalStorage) Put(id int, val interface{}) {
    33  	ls[id] = val
    34  }
    35  
    36  // GetLocalStorage retrieves the LocalStorage from the context.  This only works if the context was generated
    37  // by the pipeline package when starting the pipeline
    38  func GetLocalStorage(ctx context.Context) LocalStorage {
    39  	val := ctx.Value(localStorageKey)
    40  
    41  	if val == nil {
    42  		panic("This isn't the context for a pipeline spawned go routine, or the LocalStorage was deleted")
    43  	}
    44  
    45  	if ls, ok := val.(LocalStorage); !ok {
    46  		panic("This isn't the context for a pipeline spawned go routine, or the LocalStorage was deleted")
    47  	} else {
    48  		return ls
    49  	}
    50  }