github.com/vescale/zgraph@v0.0.0-20230410094002-959c02d50f95/catalog/catalog.go (about)

     1  // Copyright 2022 zGraph Authors. All rights reserved.
     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 catalog
    16  
    17  import (
    18  	"strings"
    19  	"sync"
    20  
    21  	"github.com/vescale/zgraph/meta"
    22  	"github.com/vescale/zgraph/storage/kv"
    23  )
    24  
    25  // Catalog maintains the catalog of graphs and label information.
    26  type Catalog struct {
    27  	// mdl prevent executing DDL concurrently.
    28  	mdl sync.Mutex
    29  
    30  	// mu protect the catalog fields.
    31  	mu     sync.RWMutex
    32  	byName map[string]*Graph
    33  	byID   map[int64]*Graph
    34  }
    35  
    36  // Load loads the catalog from a kv snapshot.
    37  func Load(snapshot kv.Snapshot) (*Catalog, error) {
    38  	c := &Catalog{
    39  		byName: map[string]*Graph{},
    40  		byID:   map[int64]*Graph{},
    41  	}
    42  
    43  	meta := meta.NewSnapshot(snapshot)
    44  	graphs, err := meta.ListGraphs()
    45  	if err != nil {
    46  		return nil, err
    47  	}
    48  	for _, g := range graphs {
    49  		// Load labels
    50  		labels, err := meta.ListLabels(g.ID)
    51  		if err != nil {
    52  			return nil, err
    53  		}
    54  		g.Labels = labels
    55  
    56  		// Load properties
    57  		properties, err := meta.ListProperties(g.ID)
    58  		if err != nil {
    59  			return nil, err
    60  		}
    61  		g.Properties = properties
    62  
    63  		// Build graph instance.
    64  		graph := NewGraph(g)
    65  		c.byName[g.Name.L] = graph
    66  		c.byID[g.ID] = graph
    67  	}
    68  
    69  	return c, nil
    70  }
    71  
    72  // Graph returns the graph of specified name.
    73  func (c *Catalog) Graph(name string) *Graph {
    74  	c.mu.RLock()
    75  	defer c.mu.RUnlock()
    76  
    77  	return c.byName[strings.ToLower(name)]
    78  }
    79  
    80  // GraphByID returns the graph of specified ID.
    81  func (c *Catalog) GraphByID(id int64) *Graph {
    82  	c.mu.RLock()
    83  	defer c.mu.RUnlock()
    84  
    85  	return c.byID[id]
    86  }
    87  
    88  // Graphs returns all graphs.
    89  func (c *Catalog) Graphs() []*Graph {
    90  	c.mu.RLock()
    91  	defer c.mu.RUnlock()
    92  
    93  	graphs := make([]*Graph, 0, len(c.byName))
    94  	for _, g := range c.byName {
    95  		graphs = append(graphs, g)
    96  	}
    97  
    98  	return graphs
    99  }
   100  
   101  // Label returns the label of specified graph.
   102  func (c *Catalog) Label(graphName, labelName string) *Label {
   103  	g := c.Graph(graphName)
   104  	if g == nil {
   105  		return nil
   106  	}
   107  
   108  	return g.Label(labelName)
   109  }
   110  
   111  // LabelByID returns the label of specified graph.
   112  func (c *Catalog) LabelByID(graphID, labelID int64) *Label {
   113  	g := c.GraphByID(graphID)
   114  	if g == nil {
   115  		return nil
   116  	}
   117  
   118  	return g.LabelByID(labelID)
   119  }
   120  
   121  // Labels returns all labels of specified graph.
   122  func (c *Catalog) Labels(graphName string) []*Label {
   123  	g := c.Graph(graphName)
   124  	if g == nil {
   125  		return nil
   126  	}
   127  
   128  	return g.Labels()
   129  }
   130  
   131  // MDLock locks the catalog to prevent executing DDL concurrently.
   132  func (c *Catalog) MDLock() {
   133  	c.mdl.Lock()
   134  }
   135  
   136  // MDUnlock unlocks the catalog.
   137  func (c *Catalog) MDUnlock() {
   138  	c.mdl.Unlock()
   139  }