summaryrefslogtreecommitdiffstats
diff options
context:
space:
mode:
authorHåvard Pettersen <havardpe@oath.com>2018-12-17 13:49:33 +0000
committerHåvard Pettersen <havardpe@oath.com>2019-01-02 12:55:19 +0000
commitf6cdd76d3ce94b587a41e04ed3153606e9c149aa (patch)
treec00f3af304cacf01f262d3d94a6e47d8f2d081b3
parent77f69efafd70cefeec471ebc8b8dd06643d24dfe (diff)
use portal in storage webserver
Diffstat
-rw-r--r--storage/src/tests/frameworkimpl/status/statustest.cpp86
-rw-r--r--storage/src/vespa/storage/frameworkimpl/status/statuswebserver.cpp242
-rw-r--r--storage/src/vespa/storage/frameworkimpl/status/statuswebserver.h29
-rw-r--r--storageframework/src/vespa/storageframework/generic/status/statusreporter.cpp12
-rw-r--r--storageframework/src/vespa/storageframework/generic/status/statusreporter.h7
5 files changed, 115 insertions, 261 deletions
diff --git a/storage/src/tests/frameworkimpl/status/statustest.cpp b/storage/src/tests/frameworkimpl/status/statustest.cpp
index 3ee9924648d..b047a4000cf 100644
--- a/storage/src/tests/frameworkimpl/status/statustest.cpp
+++ b/storage/src/tests/frameworkimpl/status/statustest.cpp
@@ -8,6 +8,29 @@
#include <tests/common/teststorageapp.h>
#include <vespa/vdstestlib/cppunit/macros.h>
#include <vespa/document/util/stringutil.h>
+#include <vespa/vespalib/net/crypto_engine.h>
+#include <vespa/vespalib/net/socket_spec.h>
+#include <vespa/vespalib/net/sync_crypto_socket.h>
+
+vespalib::string fetch(int port, const vespalib::string &path) {
+ auto crypto = vespalib::CryptoEngine::get_default();
+ auto socket = vespalib::SocketSpec::from_port(port).client_address().connect();
+ CPPUNIT_ASSERT(socket.valid());
+ auto conn = vespalib::SyncCryptoSocket::create(*crypto, std::move(socket), false);
+ vespalib::string http_req = vespalib::make_string("GET %s HTTP/1.1\r\n"
+ "Host: localhost:%d\r\n"
+ "\r\n", path.c_str(), port);
+ CPPUNIT_ASSERT_EQUAL(conn->write(http_req.data(), http_req.size()), ssize_t(http_req.size()));
+ char buf[1024];
+ vespalib::string result;
+ ssize_t res = conn->read(buf, sizeof(buf));
+ while (res > 0) {
+ result.append(vespalib::stringref(buf, res));
+ res = conn->read(buf, sizeof(buf));
+ }
+ CPPUNIT_ASSERT_EQUAL(res, ssize_t(0));
+ return result;
+}
namespace storage {
@@ -27,7 +50,6 @@ struct StatusTest : public CppUnit::TestFixture {
CPPUNIT_TEST(testHtmlStatus);
CPPUNIT_TEST(testXmlStatus);
CPPUNIT_TEST(test404);
- CPPUNIT_TEST(requireThatServerSpecIsConstructedCorrectly);
CPPUNIT_TEST_SUITE_END();
};
@@ -102,14 +124,12 @@ StatusTest::testIndexStatusPage()
"barid", "Bar impl", "<p>info</p>"));
StatusWebServer webServer(_node->getComponentRegister(),
_node->getComponentRegister(),
- "raw:httpport -1");
- std::ostringstream ss;
- framework::HttpUrlPath path("");
- webServer.handlePage(path, ss);
+ "raw:httpport 0");
+ auto actual = fetch(webServer.getListenPort(), "/");
std::string expected(
"HTTP\\/1.1 200 OK\r\n"
- "Connection: Close\r\n"
- "Content-type: text\\/html\r\n"
+ "Connection: close\r\n"
+ "Content-Type: text\\/html\r\n"
"\r\n"
"<html>\n"
"<head>\n"
@@ -123,7 +143,7 @@ StatusTest::testIndexStatusPage()
"<\\/body>\n"
"<\\/html>\n"
);
- CPPUNIT_ASSERT_MATCH_REGEX(expected, ss.str());
+ CPPUNIT_ASSERT_MATCH_REGEX(expected, actual);
}
void
@@ -134,14 +154,12 @@ StatusTest::testHtmlStatus()
"fooid", "Foo impl", "<p>info</p>", "<!-- script -->"));
StatusWebServer webServer(_node->getComponentRegister(),
_node->getComponentRegister(),
- "raw:httpport -1");
- std::ostringstream ost;
- framework::HttpUrlPath path("/fooid?unusedParam");
- webServer.handlePage(path, ost);
+ "raw:httpport 0");
+ auto actual = fetch(webServer.getListenPort(), "/fooid?unusedParam");
std::string expected(
"HTTP/1.1 200 OK\r\n"
- "Connection: Close\r\n"
- "Content-type: text/html\r\n"
+ "Connection: close\r\n"
+ "Content-Type: text/html\r\n"
"\r\n"
"<html>\n"
"<head>\n"
@@ -152,7 +170,7 @@ StatusTest::testHtmlStatus()
"<p>info</p></body>\n"
"</html>\n"
);
- CPPUNIT_ASSERT_EQUAL(expected, ost.str());
+ CPPUNIT_ASSERT_EQUAL(expected, std::string(actual));
}
void
@@ -163,21 +181,19 @@ StatusTest::testXmlStatus()
"fooid", "Foo impl"));
StatusWebServer webServer(_node->getComponentRegister(),
_node->getComponentRegister(),
- "raw:httpport -1");
- std::ostringstream ost;
- framework::HttpUrlPath path("/fooid?unusedParam");
- webServer.handlePage(path, ost);
+ "raw:httpport 0");
+ auto actual = fetch(webServer.getListenPort(), "/fooid?unusedParam");
std::string expected(
"HTTP/1.1 200 OK\r\n"
- "Connection: Close\r\n"
- "Content-type: application/xml\r\n"
+ "Connection: close\r\n"
+ "Content-Type: application/xml\r\n"
"\r\n"
"<?xml version=\"1.0\"?>\n"
"<status id=\"fooid\" name=\"Foo impl\">\n"
"<mytag foo=\"bar\">content</mytag>\n"
"</status>"
);
- CPPUNIT_ASSERT_EQUAL(expected, ost.str());
+ CPPUNIT_ASSERT_EQUAL(expected, std::string(actual));
}
void
@@ -185,30 +201,14 @@ StatusTest::test404()
{
StatusWebServer webServer(_node->getComponentRegister(),
_node->getComponentRegister(),
- "raw:httpport -1");
- std::ostringstream ost;
- framework::HttpUrlPath path("/fooid?unusedParam");
- webServer.handlePage(path, ost);
+ "raw:httpport 0");
+ auto actual = fetch(webServer.getListenPort(), "/fooid?unusedParam");
std::string expected(
- "HTTP/1.1 404 Not found\r\n"
- "Connection: Close\r\n"
- "Content-type: text/html\r\n"
+ "HTTP/1.1 404 Not Found\r\n"
+ "Connection: close\r\n"
"\r\n"
- "<html><head><title>404 Not found</title></head>\r\n"
- "<body><h1>404 Not found</h1>\r\n"
- "<p></p></body>\r\n"
- "</html>\r\n"
);
- CPPUNIT_ASSERT_EQUAL_ESCAPED(expected, ost.str());
-}
-
-void
-StatusTest::requireThatServerSpecIsConstructedCorrectly()
-{
- CPPUNIT_ASSERT_EQUAL(vespalib::string("requesthost:10"),
- StatusWebServer::getServerSpec("requesthost:10", "serverhost:20"));
- CPPUNIT_ASSERT_EQUAL(vespalib::string("serverhost:20"),
- StatusWebServer::getServerSpec("", "serverhost:20"));
+ CPPUNIT_ASSERT_EQUAL_ESCAPED(expected, std::string(actual));
}
} // storage
diff --git a/storage/src/vespa/storage/frameworkimpl/status/statuswebserver.cpp b/storage/src/vespa/storage/frameworkimpl/status/statuswebserver.cpp
index c7d8bf24e82..cf38eff4dfe 100644
--- a/storage/src/vespa/storage/frameworkimpl/status/statuswebserver.cpp
+++ b/storage/src/vespa/storage/frameworkimpl/status/statuswebserver.cpp
@@ -7,6 +7,8 @@
#include <vespa/vespalib/util/host_name.h>
#include <vespa/vespalib/util/exceptions.h>
#include <vespa/vespalib/component/vtag.h>
+#include <vespa/vespalib/net/crypto_engine.h>
+#include <functional>
#include <vespa/log/log.h>
LOG_SETUP(".status");
@@ -22,16 +24,10 @@ StatusWebServer::StatusWebServer(
_port(0),
_httpServer(),
_configFetcher(configUri.getContext()),
- _queuedRequests(),
- _component(std::make_unique<framework::Component>(componentRegister, "Status")),
- _thread()
+ _component(std::make_unique<framework::Component>(componentRegister, "Status"))
{
_configFetcher.subscribe<vespa::config::content::core::StorStatusConfig>(configUri.getConfigId(), this);
_configFetcher.start();
- framework::MilliSecTime maxProcessingTime(60 * 60 * 1000);
- framework::MilliSecTime maxWaitTime(10 * 1000);
- _thread = _component->startThread(*this, maxProcessingTime, maxWaitTime);
-
}
StatusWebServer::~StatusWebServer()
@@ -44,11 +40,6 @@ StatusWebServer::~StatusWebServer()
}
// Delete http server to ensure that no more incoming requests reach us.
_httpServer.reset(0);
-
- // Stop internal thread such that we don't process anymore web requests
- if (_thread.get() != 0) {
- _thread->interruptAndJoin(&_workerMonitor);
- }
}
void StatusWebServer::configure(std::unique_ptr<vespa::config::content::core::StorStatusConfig> config)
@@ -65,37 +56,6 @@ void StatusWebServer::configure(std::unique_ptr<vespa::config::content::core::St
// Negative port number means don't run the web server
if (newPort >= 0) {
server.reset(new WebServer(*this, newPort));
- server->SetKeepAlive(false);
-
- bool started = false;
- switch (server->Start()) {
- case FASTLIB_SUCCESS:
- started = true;
- break;
- case FASTLIB_HTTPSERVER_BADLISTEN:
- LOG(warning, "Listen failed on port %u", newPort);
- break;
- case FASTLIB_HTTPSERVER_NEWTHREADFAILED:
- LOG(warning, "Failed starting thread for status server on port %u", newPort);
- break;
- case FASTLIB_HTTPSERVER_ALREADYSTARTED:
- LOG(warning, "Failed starting status server on port %u (already started?)", newPort);
- break;
- default:
- LOG(warning, "Failed starting status server on port %u (unknown reason)", newPort);
- break;
- }
- if (!started) {
- std::ostringstream ost;
- ost << "Failed to start status HTTP server using port " << newPort << ".";
- if (_httpServer) {
- ost << " Status server still running on port " << _port << " instead of suggested port " << newPort;
- }
- LOG(fatal, "%s.", ost.str().c_str());
- _component->requestShutdown(ost.str());
- _httpServer.reset();
- return;
- }
// Now that we know config update went well, update internal state
_port = server->getListenPort();
LOG(config, "Status pages now available on port %u", _port);
@@ -112,45 +72,47 @@ void StatusWebServer::configure(std::unique_ptr<vespa::config::content::core::St
}
StatusWebServer::WebServer::WebServer(StatusWebServer& status, uint16_t port)
- : Fast_HTTPServer(port, NULL, 100, false, 128*1024, 10),
- _status(status),
- _serverSpec(vespalib::make_string("%s:%d", vespalib::HostName::get().c_str(), port))
+ : _status(status),
+ _server(vespalib::Portal::create(vespalib::CryptoEngine::get_default(), port)),
+ _executor(1, 256 * 1024),
+ _root(_server->bind("/", *this))
{
}
+StatusWebServer::WebServer::~WebServer()
+{
+ _root.reset();
+ _executor.shutdown().sync();
+}
namespace {
- /** Utility class for printing HTTP errors. */
- struct HttpErrorWriter {
- std::ostream& _out;
- HttpErrorWriter(std::ostream& out, vespalib::stringref error)
- : _out(out)
- {
- _out << "HTTP/1.1 " << error << "\r\n"
- "Connection: Close\r\n"
- "Content-type: text/html\r\n\r\n"
- "<html><head><title>" << error << "</title></head>\r\n"
- "<body><h1>" << error << "</h1>\r\n"
- "<p>";
- }
+struct HandleGetTask : vespalib::Executor::Task {
+ vespalib::Portal::GetRequest request;
+ std::function<void(vespalib::Portal::GetRequest)> fun;
+ HandleGetTask(vespalib::Portal::GetRequest request_in,
+ std::function<void(vespalib::Portal::GetRequest)> fun_in)
+ : request(std::move(request_in)), fun(fun_in) {}
+ void run() override { fun(std::move(request)); }
+};
- template<typename T>
- HttpErrorWriter& operator<<(const T& t) {
- _out << t;
- return *this;
- }
+}
- ~HttpErrorWriter() {
- _out << "</p></body>\r\n"
- "</html>\r\n";
- }
- };
+
+void
+StatusWebServer::WebServer::get(vespalib::Portal::GetRequest request)
+{
+ auto fun = [this](vespalib::Portal::GetRequest req)
+ {
+ handle_get(std::move(req));
+ };
+ _executor.execute(std::make_unique<HandleGetTask>(std::move(request), std::move(fun)));
}
void
-StatusWebServer::WebServer::onGetRequest(const string & tmpurl, const string &serverSpec, Fast_HTTPConnection& conn)
+StatusWebServer::WebServer::handle_get(vespalib::Portal::GetRequest request)
{
+ const vespalib::string &tmpurl = request.get_uri();
Fast_URL urlCodec;
int bufLength = tmpurl.length() * 2 + 10;
char * encodedUrl = new char[bufLength];
@@ -160,65 +122,11 @@ StatusWebServer::WebServer::onGetRequest(const string & tmpurl, const string &se
urlCodec.decode(encodedUrl, decodedUrl, bufLength);
delete [] encodedUrl;
- string url = decodedUrl;
+ vespalib::string url = decodedUrl;
LOG(debug, "Status got get request '%s'", url.c_str());
- framework::HttpUrlPath urlpath(url.c_str(),
- StatusWebServer::getServerSpec(serverSpec, getServerSpec()));
- std::string link(urlpath.getPath());
- if (link.size() > 0 && link[0] == '/') link = link.substr(1);
- // Only allow crucial components not locking to answer directly.
- // (We want deadlockdetector status page to be available during a
- // deadlock
- if (link == "" || link == "deadlockdetector") {
- std::ostringstream ost;
- _status.handlePage(urlpath, ost);
- conn.Output(ost.str().c_str());
- } else {
- // Route other status requests that can possibly deadlock to a
- // worker thread.
- vespalib::MonitorGuard monitor(_status._workerMonitor);
- _status._queuedRequests.emplace_back(std::make_shared<HttpRequest>(url.c_str(), urlpath.getServerSpec()));
- HttpRequest* req = _status._queuedRequests.back().get();
- framework::SecondTime timeout(urlpath.get("timeout", 30u));
- framework::SecondTime timeoutTime(_status._component->getClock().getTimeInSeconds() + timeout);
- monitor.signal();
- while (true) {
- monitor.wait(100);
- bool done = false;
- if (req->_result.get()) {
- conn.Output(req->_result->c_str());
- LOG(debug, "Finished status request for '%s'", req->_url.c_str());
- done = true;
- } else {
- if (_status._component->getClock().getTimeInSeconds() > timeoutTime)
- {
- std::ostringstream ost;
- {
- HttpErrorWriter writer(ost, "500 Internal Server Error");
- writer << "Request " << url.c_str() << " timed out "
- << "after " << timeout << " seconds.";
- }
- LOG(debug, "HTTP status request failed: %s. %zu requests queued",
- ost.str().c_str(), _status._queuedRequests.size() - 1);
- conn.Output(ost.str().c_str());
- done = true;
- }
- }
- if (done) {
- for (std::list<HttpRequest::SP>::iterator it
- = _status._queuedRequests.begin();
- it != _status._queuedRequests.end(); ++it)
- {
- if (it->get() == req) {
- _status._queuedRequests.erase(it);
- break;
- }
- }
- break;
- }
- }
- }
+ framework::HttpUrlPath urlpath(url.c_str(), request.get_host());
+ _status.handlePage(urlpath, std::move(request));
}
namespace {
@@ -236,8 +144,15 @@ namespace {
};
}
+
+int
+StatusWebServer::getListenPort() const
+{
+ return _httpServer ? _httpServer->getListenPort() : -1;
+}
+
void
-StatusWebServer::handlePage(const framework::HttpUrlPath& urlpath, std::ostream& out)
+StatusWebServer::handlePage(const framework::HttpUrlPath& urlpath, vespalib::Portal::GetRequest request)
{
vespalib::string link(urlpath.getPath());
if (link.size() > 0 && link[0] == '/') link = link.substr(1);
@@ -245,28 +160,23 @@ StatusWebServer::handlePage(const framework::HttpUrlPath& urlpath, std::ostream&
size_t slashPos = link.find('/');
if (slashPos != std::string::npos) link = link.substr(0, slashPos);
- bool pageExisted = false;
if ( ! link.empty()) {
const framework::StatusReporter *reporter = _reporterMap.getStatusReporter(link);
if (reporter != nullptr) {
try {
- pageExisted = reporter->reportHttpHeader(out, urlpath);
- if (pageExisted) {
- pageExisted = reporter->reportStatus(out, urlpath);
+ std::ostringstream content;
+ auto content_type = reporter->getReportContentType(urlpath);
+ if (reporter->reportStatus(content, urlpath)) {
+ request.respond_with_content(content_type, content.str());
+ } else {
+ request.respond_with_error(404, "Not Found");
}
} catch (std::exception &e) {
- HttpErrorWriter writer(out, "500 Internal Server Error");
- writer << "<pre>" << e.what() << "</pre>";
- pageExisted = true;
- }
- if (pageExisted) {
- LOG(spam, "Status finished request");
- return;
+ request.respond_with_error(500, "Internal Server Error");
}
+ } else {
+ request.respond_with_error(404, "Not Found");
}
- }
- if (!pageExisted && link.size() > 0) {
- HttpErrorWriter writer(out, "404 Not found");
} else {
IndexPageReporter indexRep;
indexRep << "<p><b>Binary version of Vespa:</b> "
@@ -278,52 +188,12 @@ StatusWebServer::handlePage(const framework::HttpUrlPath& urlpath, std::ostream&
<< reporter->getName() << "</a><br>\n";
}
}
- indexRep.reportHttpHeader(out, urlpath);
- indexRep.reportStatus(out, urlpath);
+ std::ostringstream content;
+ auto content_type = indexRep.getReportContentType(urlpath);
+ indexRep.reportStatus(content, urlpath);
+ request.respond_with_content(content_type, content.str());
}
LOG(spam, "Status finished request");
}
-vespalib::string
-StatusWebServer::getServerSpec(const vespalib::string &specFromRequest,
- const vespalib::string &specFromServer)
-{
- if (specFromRequest.empty()) {
- // This is a fallback in case the request spec is not given (HTTP 1.0 header)
- return specFromServer;
- }
- return specFromRequest;
-}
-
-void
-StatusWebServer::run(framework::ThreadHandle& thread)
-{
- while (!thread.interrupted()) {
- HttpRequest::SP request;
- {
- vespalib::MonitorGuard monitor(_workerMonitor);
- for (const HttpRequest::SP & cur : _queuedRequests) {
- if ( ! cur->_result ) {
- request = cur;
- break;
- }
- }
- if (!request.get()) {
- monitor.wait(10 * 1000);
- thread.registerTick(framework::WAIT_CYCLE);
- continue;
- }
- }
- framework::HttpUrlPath urlpath(request->_url, request->_serverSpec);
- std::ostringstream ost;
- handlePage(urlpath, ost);
- // If the same request is still in front of the queue
- // (it hasn't timed out), add the result to it.
- vespalib::MonitorGuard monitor(_workerMonitor);
- request->_result.reset(new vespalib::string(ost.str()));
- monitor.signal();
- thread.registerTick(framework::PROCESS_CYCLE);
- }
-}
-
} // storage
diff --git a/storage/src/vespa/storage/frameworkimpl/status/statuswebserver.h b/storage/src/vespa/storage/frameworkimpl/status/statuswebserver.h
index fe716b4212c..756a895afb8 100644
--- a/storage/src/vespa/storage/frameworkimpl/status/statuswebserver.h
+++ b/storage/src/vespa/storage/frameworkimpl/status/statuswebserver.h
@@ -14,7 +14,8 @@
#include <vespa/storageframework/generic/thread/runnable.h>
#include <vespa/config/config.h>
#include <vespa/config/helper/configfetcher.h>
-#include <vespa/fastlib/net/httpserver.h>
+#include <vespa/vespalib/portal/portal.h>
+#include <vespa/vespalib/util/threadstackexecutor.h>
#include <list>
namespace storage {
@@ -30,16 +31,21 @@ namespace framework {
class StatusWebServer : private config::IFetcherCallback<vespa::config::content::core::StorStatusConfig>,
private framework::Runnable
{
- class WebServer : public Fast_HTTPServer {
+ class WebServer : public vespalib::Portal::GetHandler {
StatusWebServer& _status;
- vespalib::string _serverSpec;
+ vespalib::Portal::SP _server;
+ vespalib::ThreadStackExecutor _executor;
+ vespalib::Portal::Token::UP _root;
public:
WebServer(StatusWebServer&, uint16_t port);
+ ~WebServer();
+
+ void get(vespalib::Portal::GetRequest request) override;
+ void handle_get(vespalib::Portal::GetRequest request);
- void onGetRequest(const string & url, const string & serverSpec, Fast_HTTPConnection& conn) override;
- const vespalib::string &getServerSpec() const {
- return _serverSpec;
+ int getListenPort() const {
+ return _server->listen_port();
}
};
struct HttpRequest {
@@ -61,9 +67,7 @@ class StatusWebServer : private config::IFetcherCallback<vespa::config::content:
uint16_t _port;
std::unique_ptr<WebServer> _httpServer;
config::ConfigFetcher _configFetcher;
- std::list<HttpRequest::SP> _queuedRequests;
std::unique_ptr<framework::Component> _component;
- std::unique_ptr<framework::Thread> _thread;
public:
StatusWebServer(const StatusWebServer &) = delete;
@@ -72,14 +76,11 @@ public:
framework::StatusReporterMap&,
const config::ConfigUri & configUri);
~StatusWebServer() override;
-
- void handlePage(const framework::HttpUrlPath&, std::ostream& out);
- static vespalib::string getServerSpec(const vespalib::string &requestSpec,
- const vespalib::string &serverSpec);
+ int getListenPort() const;
+ void handlePage(const framework::HttpUrlPath&, vespalib::Portal::GetRequest request);
private:
void configure(std::unique_ptr<vespa::config::content::core::StorStatusConfig> config) override;
- void getPage(const char* url, Fast_HTTPConnection& conn);
- void run(framework::ThreadHandle&) override;
+ void run(framework::ThreadHandle&) override {}
};
}
diff --git a/storageframework/src/vespa/storageframework/generic/status/statusreporter.cpp b/storageframework/src/vespa/storageframework/generic/status/statusreporter.cpp
index b17c70d132e..c7d025b060f 100644
--- a/storageframework/src/vespa/storageframework/generic/status/statusreporter.cpp
+++ b/storageframework/src/vespa/storageframework/generic/status/statusreporter.cpp
@@ -15,17 +15,5 @@ StatusReporter::~StatusReporter()
{
}
-bool
-StatusReporter::reportHttpHeader(std::ostream& out,
- const HttpUrlPath& path) const
-{
- vespalib::string contentType(getReportContentType(path));
- if (contentType == "") return false;
- out << "HTTP/1.1 200 OK\r\n"
- "Connection: Close\r\n"
- "Content-type: " << contentType << "\r\n\r\n";
- return true;
-}
-
} // framework
} // storage
diff --git a/storageframework/src/vespa/storageframework/generic/status/statusreporter.h b/storageframework/src/vespa/storageframework/generic/status/statusreporter.h
index 64e7c7b62e7..8d58467a221 100644
--- a/storageframework/src/vespa/storageframework/generic/status/statusreporter.h
+++ b/storageframework/src/vespa/storageframework/generic/status/statusreporter.h
@@ -40,12 +40,7 @@ struct StatusReporter
virtual bool isValidStatusRequest() const { return true; }
/**
- * Overwrite to get full control of header writes.
- * Returning false means the page specified by path does not exist.
- */
- virtual bool reportHttpHeader(std::ostream&, const HttpUrlPath&) const;
- /**
- * Called by default writeHttpHeader implementation to get content type.
+ * Called to get content type.
* An empty string indicates page not found.
*/
virtual vespalib::string getReportContentType(const HttpUrlPath&) const = 0;