1 files changed, 192 insertions, 0 deletions
diff --git a/web/log.js b/web/log.js
new file mode 100644
index 0000000..36fd553
--- /dev/null
+++ b/web/log.js
@@ -0,0 +1,192 @@
+/* Copyright (c) 2012: Daniel Richman. License: GNU GPL 3 */
+/* Additional features: Priyesh Patel                     */
+
+(function () {
+
+var dataelem = "#data";
+var pausetoggle = "#pause";
+var scrollelems = ["html", "body"];
+
+var url = "/var/log/compute-tools/container.log";
+var fix_rn = true;
+var load = 10 * 1024; /* 10KB */
+var poll = 1000; /* 1s */
+
+var kill = false;
+var loading = false;
+var pause = false;
+var reverse = true;
+var log_data = "";
+var log_file_size = 0;
+
+/* :-( https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/parseInt */
+function parseInt2(value) {
+    if(!(/^[0-9]+$/.test(value))) throw "Invalid integer " + value;
+    var v = Number(value);
+    if (isNaN(v))                 throw "Invalid integer " + value;
+    return v;
+}
+
+function get_log() {
+    if (kill | loading) return;
+    loading = true;
+
+    var range;
+    var first_load;
+    var must_get_206;
+    if (log_file_size === 0) {
+        /* Get the last 'load' bytes */
+        range = "-" + load.toString();
+        first_load = true;
+        must_get_206 = false;
+    } else {
+        /* Get the (log_file_size - 1)th byte, onwards. */
+        range = (log_file_size - 1).toString() + "-";
+        first_load = false;
+        must_get_206 = log_file_size > 1;
+    }
+
+    /* The "log_file_size - 1" deliberately reloads the last byte, which we already
+     * have. This is to prevent a 416 "Range unsatisfiable" error: a response
+     * of length 1 tells us that the file hasn't changed yet. A 416 shows that
+     * the file has been trucnated */
+
+    $.ajax(url, {
+        dataType: "text",
+        cache: false,
+        headers: {Range: "bytes=" + range},
+        success: function (data, s, xhr) {
+            loading = false;
+
+            var content_size;
+
+            if (xhr.status === 206) {
+                var c_r = xhr.getResponseHeader("Content-Range");
+                if (!c_r)
+                    throw "Server did not respond with a Content-Range";
+
+                log_file_size = parseInt2(c_r.split("/")[1]);
+                content_size = parseInt2(xhr.getResponseHeader("Content-Length"));
+            } else if (xhr.status === 200) {
+                if (must_get_206)
+                    throw "Expected 206 Partial Content";
+
+                content_size = log_file_size =
+                        parseInt2(xhr.getResponseHeader("Content-Length"));
+            } else {
+                throw "Unexpected status " + xhr.status;
+            }
+
+            if (first_load && data.length > load)
+                throw "Server's response was too long";
+
+            var added = false;
+
+            if (first_load) {
+                /* Clip leading part-line if not the whole file */
+                if (content_size < log_file_size) {
+                    var start = data.indexOf("\n");
+                    log_data = data.substring(start + 1);
+                } else {
+                    log_data = data;
+                }
+
+                added = true;
+            } else {
+                /* Drop the first byte (see above) */
+                log_data += data.substring(1);
+
+                if (log_data.length > load) {
+                    var start = log_data.indexOf("\n", log_data.length - load);
+                    log_data = log_data.substring(start + 1);
+                }
+
+                if (data.length > 1)
+                    added = true;
+            }
+
+            if (added)
+                show_log(added);
+            setTimeout(get_log, poll);
+        },
+        error: function (xhr, s, t) {
+            loading = false;
+
+            if (xhr.status === 416 || xhr.status == 404) {
+                /* 416: Requested range not satisfiable: log was truncated. */
+                /* 404: Retry soon, I guess */
+
+                log_file_size = 0;
+                log_data = "";
+                show_log();
+
+                setTimeout(get_log, poll);
+            } else {
+                throw "Unknown AJAX Error (status " + xhr.status + ")";
+            }
+        }
+    });
+}
+
+function scroll(where) {
+    for (var i = 0; i < scrollelems.length; i++) {
+        var s = $(scrollelems[i]);
+        if (where === -1)
+            s.scrollTop(s.height());
+        else
+            s.scrollTop(where);
+    }
+}
+
+function show_log() {
+    if (pause) return;
+
+    var t = log_data;
+
+    if (reverse) {
+        var t_a = t.split(/\n/g);
+        t_a.reverse();
+        if (t_a[0] == "") 
+            t_a.shift();
+        t = t_a.join("\n");
+    }
+
+    if (fix_rn)
+        t = t.replace(/\n/g, "\r\n");
+
+    $(dataelem).text(t);
+    if (!reverse)
+        scroll(-1);
+}
+
+function error(what) {
+    kill = true;
+
+    $(dataelem).text("An error occured :-(.\r\n" +
+                     "Reloading may help; no promises.\r\n" + 
+                     what);
+    scroll(0);
+
+    return false;
+}
+
+$(document).ready(function () {
+    window.onerror = error;
+
+    /* If URL is /logtail/?noreverse display in chronological order */
+    var hash = location.search.replace(/^\?/, "");
+    if (hash == "noreverse")
+        reverse = false;
+
+    /* Add pause toggle */
+    $(pausetoggle).click(function (e) {
+        pause = !pause;
+        $(pausetoggle).text(pause ? "Unpause" : "Pause");
+        show_log();
+        e.preventDefault();
+    });
+
+    get_log();
+});
+
+})();