Merge pull request #170 from mattermost/mm-1420

Fixes mm-1420 adding initial support for postgres

1 files changed, 102 insertions, 0 deletions

diff --git a/Godeps/_workspace/src/github.com/lib/pq/listen_example/doc.go b/Godeps/_workspace/src/github.com/lib/pq/listen_example/doc.go
new file mode 100644
index 000000000..5bc99f5c1
--- /dev/null
+++ b/Godeps/_workspace/src/github.com/lib/pq/listen_example/doc.go
@@ -0,0 +1,102 @@
+/*
+
+Below you will find a self-contained Go program which uses the LISTEN / NOTIFY
+mechanism to avoid polling the database while waiting for more work to arrive.
+
+    //
+    // You can see the program in action by defining a function similar to
+    // the following:
+    //
+    // CREATE OR REPLACE FUNCTION public.get_work()
+    //   RETURNS bigint
+    //   LANGUAGE sql
+    //   AS $$
+    //     SELECT CASE WHEN random() >= 0.2 THEN int8 '1' END
+    //   $$
+    // ;
+
+    package main
+
+    import (
+        "database/sql"
+        "fmt"
+        "time"
+
+        "github.com/lib/pq"
+    )
+
+    func doWork(db *sql.DB, work int64) {
+        // work here
+    }
+
+    func getWork(db *sql.DB) {
+        for {
+            // get work from the database here
+            var work sql.NullInt64
+            err := db.QueryRow("SELECT get_work()").Scan(&work)
+            if err != nil {
+                fmt.Println("call to get_work() failed: ", err)
+                time.Sleep(10 * time.Second)
+                continue
+            }
+            if !work.Valid {
+                // no more work to do
+                fmt.Println("ran out of work")
+                return
+            }
+
+            fmt.Println("starting work on ", work.Int64)
+            go doWork(db, work.Int64)
+        }
+    }
+
+    func waitForNotification(l *pq.Listener) {
+        for {
+            select {
+                case <-l.Notify:
+                    fmt.Println("received notification, new work available")
+                    return
+                case <-time.After(90 * time.Second):
+                    go func() {
+                        l.Ping()
+                    }()
+                    // Check if there's more work available, just in case it takes
+                    // a while for the Listener to notice connection loss and
+                    // reconnect.
+                    fmt.Println("received no work for 90 seconds, checking for new work")
+                    return
+            }
+        }
+    }
+
+    func main() {
+        var conninfo string = ""
+
+        db, err := sql.Open("postgres", conninfo)
+        if err != nil {
+            panic(err)
+        }
+
+        reportProblem := func(ev pq.ListenerEventType, err error) {
+            if err != nil {
+                fmt.Println(err.Error())
+            }
+        }
+
+        listener := pq.NewListener(conninfo, 10 * time.Second, time.Minute, reportProblem)
+        err = listener.Listen("getwork")
+        if err != nil {
+            panic(err)
+        }
+
+        fmt.Println("entering main loop")
+        for {
+            // process all available work before waiting for notifications
+            getWork(db)
+            waitForNotification(listener)
+        }
+    }
+
+
+*/
+package listen_example