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comparison src/fschmidt/util/servlet/DbCache.java @ 68:00520880ad02

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add fschmidt source
author Franklin Schmidt <fschmidt@gmail.com>
date Sun, 05 Oct 2025 17:24:15 -0600
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67:9d0fefce6985 68:00520880ad02
1 /*
2 Copyright (c) 2008 Franklin Schmidt <fschmidt@gmail.com>
3
4 Permission is hereby granted, free of charge, to any person obtaining a copy
5 of this software and associated documentation files (the "Software"), to deal
6 in the Software without restriction, including without limitation the rights
7 to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
8 copies of the Software, and to permit persons to whom the Software is
9 furnished to do so, subject to the following conditions:
10
11 The above copyright notice and this permission notice shall be included in
12 all copies or substantial portions of the Software.
13
14 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
15 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
16 FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
17 AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
18 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
19 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
20 THE SOFTWARE.
21 */
22
23 package fschmidt.util.servlet;
24
25 import java.sql.Connection;
26 import java.sql.PreparedStatement;
27 import java.sql.ResultSet;
28 import java.sql.SQLException;
29 import java.sql.Statement;
30 import java.util.Date;
31 import java.util.Map;
32 import java.util.HashMap;
33 import fschmidt.db.DbDatabase;
34 import fschmidt.db.postgres.DbDatabaseImpl;
35
36
37 public final class DbCache implements HttpCache {
38 private final DbDatabase db;
39 private long lastClear;
40 private static final String LAST_CLEAR = "_last_clear";
41
42 public DbCache(DbDatabase db) {
43 this.db = db;
44 setLastClear();
45 }
46
47 private void setLastClear() {
48 try {
49 Connection con = db.getConnection();
50 try {
51 PreparedStatement stmt = con.prepareStatement(
52 "select last_modified from http_cache where event=?"
53 );
54 stmt.setString(1,LAST_CLEAR);
55 ResultSet rs = stmt.executeQuery();
56 if( !rs.next() ) {
57 modified(LAST_CLEAR);
58 stmt.setString(1,LAST_CLEAR);
59 rs = stmt.executeQuery();
60 rs.next();
61 }
62 lastClear = getLastModified(rs);
63 stmt.close();
64 } finally {
65 con.close();
66 }
67 } catch(SQLException e) {
68 throw new RuntimeException(e);
69 }
70 }
71
72 private static long getLastModified(ResultSet rs) throws SQLException {
73 return rs.getTimestamp("last_modified").getTime()/1000*1000;
74 }
75
76 public long[] lastModifieds(final String[] modifyingEvents) {
77 switch( modifyingEvents.length ) {
78 case 0:
79 return new long[0];
80 case 1:
81 try {
82 Connection con = db.getConnection();
83 PreparedStatement stmt = con.prepareStatement(
84 "select last_modified from http_cache where event=?"
85 );
86 try {
87 stmt.setString(1,modifyingEvents[0].toString());
88 ResultSet rs = stmt.executeQuery();
89 return new long[]{ rs.next() ? getLastModified(rs) : lastClear };
90 } finally {
91 stmt.close();
92 con.close();
93 }
94 } catch(SQLException e) {
95 throw new RuntimeException(e);
96 }
97 default:
98 StringBuilder select = new StringBuilder();
99 try {
100 final String[] events = new String[modifyingEvents.length];
101 final long[] rtn = new long[modifyingEvents.length];
102 for( int i=0; i<modifyingEvents.length; i++ ) {
103 events[i] = modifyingEvents[i].toString();
104 rtn[i] = lastClear;
105 }
106 Map<String,Long> map = new HashMap<String,Long>();
107 select.append(
108 "select event,last_modified from http_cache where event in ("
109 ).append( db.arcana().quote(events[0]) );
110 for( int i=1; i<events.length; i++ ) {
111 select.append( ',' ).append( db.arcana().quote(events[i]) );
112 }
113 select.append( ")" );
114 Connection con = db.getConnection();
115 try {
116 Statement stmt = con.createStatement();
117 ResultSet rs = stmt.executeQuery( select.toString() );
118 while( rs.next() ) {
119 map.put( rs.getString("event"), getLastModified(rs) );
120 }
121 stmt.close();
122 } finally {
123 con.close();
124 }
125 for( int i=0; !map.isEmpty(); i++ ) {
126 Long lm = map.remove(events[i]);
127 if( lm != null )
128 rtn[i] = lm;
129 }
130 return rtn;
131 } catch(SQLException e) {
132 throw new RuntimeException(select.toString(),e);
133 }
134 }
135 }
136
137 public void modified(final String event) {
138 db.runAfterCommit(new Runnable(){public void run(){
139 try {
140 Connection con = db.getConnection();
141 try {
142 boolean didUpdate;
143 {
144 PreparedStatement stmt = con.prepareStatement(
145 "update http_cache set last_modified=now() where event = ?"
146 );
147 stmt.setString(1,event);
148 didUpdate = stmt.executeUpdate() > 0;
149 stmt.close();
150 }
151 if( !didUpdate ) {
152 PreparedStatement stmt = con.prepareStatement(
153 "insert into http_cache (event) values (?)"
154 );
155 stmt.setString(1,event);
156 DbDatabaseImpl.executeUpdateIgnoringDuplicateKeys(stmt);
157 stmt.close();
158 }
159 } finally {
160 con.close();
161 }
162 } catch(SQLException e) {
163 throw new RuntimeException("event = "+event,e);
164 }
165 }});
166 }
167
168 public void clear() {
169 try {
170 Connection con = db.getConnection();
171 try {
172 Statement stmt = con.createStatement();
173 stmt.executeUpdate(
174 "delete from http_cache"
175 );
176 stmt.close();
177 } finally {
178 con.close();
179 }
180 } catch(SQLException e) {
181 throw new RuntimeException(e);
182 }
183 setLastClear();
184 }
185
186 /*
187 assumes:
188
189 create table http_cache (
190 event varchar not null primary key,
191 last_modified timestamp with time zone NOT NULL DEFAULT now()
192 );
193 */
194 }