/** {@inheritDoc} */
  @Nullable
  @Override
  public GridDeployment explicitDeploy(Class<?> cls, ClassLoader clsLdr) throws GridException {
    try {
      // Make sure not to deploy peer loaded tasks with non-local class loader,
      // if local one exists.
      if (clsLdr.getClass().equals(GridDeploymentClassLoader.class)) clsLdr = clsLdr.getParent();

      GridDeployment dep;

      synchronized (mux) {
        boolean deployed = spi.register(clsLdr, cls);

        if (deployed) {
          dep = getDeployment(cls.getName());

          if (dep == null) {
            GridDeploymentResource rsrc = spi.findResource(cls.getName());

            if (rsrc != null && rsrc.getClassLoader() == clsLdr) {
              dep =
                  deploy(
                      ctx.config().getDeploymentMode(),
                      rsrc.getClassLoader(),
                      rsrc.getResourceClass(),
                      rsrc.getName());
            }
          }

          if (dep != null) {
            recordDeploy(cls, cls.getName(), true);
          }
        } else {
          dep = getDeployment(cls.getName());
        }
      }

      return dep;
    } catch (GridSpiException e) {
      recordDeployFailed(cls, clsLdr, true);

      // Avoid double wrapping.
      if (e.getCause() instanceof GridException) {
        throw (GridException) e.getCause();
      }

      throw new GridException("Failed to deploy class: " + cls.getName(), e);
    }
  }
  /** {@inheritDoc} */
  @Override
  public URL getResource(String name) {
    URL url = findResource(name);

    if (url == null) url = ClassLoader.getSystemResource(name);

    if (url == null) url = super.getResource(name);

    return url;
  }
  /** {@inheritDoc} */
  @Override
  public InputStream getResourceAsStream(String name) {
    // Find resource in GAR file first.
    InputStream in = getResourceAsStreamGarOnly(name);

    // Find resource in parent class loader.
    if (in == null) in = ClassLoader.getSystemResourceAsStream(name);

    if (in == null) in = super.getResourceAsStream(name);

    return in;
  }
  /** {@inheritDoc} */
  @Nullable
  @SuppressWarnings({"UnusedCatchParameter"})
  @Override
  public GridDeployment getDeployment(GridDeploymentMetadata meta) {
    GridDeployment dep;

    Class<?> cls = null;

    String alias = meta.alias();

    synchronized (mux) {
      // Validate metadata.
      assert meta.alias() != null;

      dep = getDeployment(meta.alias());

      if (dep != null) {
        if (log.isDebugEnabled()) {
          log.debug("Acquired deployment class from local cache: " + dep);
        }

        return dep;
      }

      GridDeploymentResource rsrc = spi.findResource(meta.alias());

      if (rsrc != null) {
        dep =
            deploy(
                ctx.config().getDeploymentMode(),
                rsrc.getClassLoader(),
                rsrc.getResourceClass(),
                alias);

        if (dep == null) {
          return null;
        }

        if (log.isDebugEnabled()) {
          log.debug("Acquired deployment class from SPI: " + dep);
        }
      }
      // Auto-deploy.
      else {
        ClassLoader ldr = meta.classLoader();

        if (ldr == null) {
          ldr = Thread.currentThread().getContextClassLoader();

          // Safety.
          if (ldr == null) {
            ldr = ctxLdr;
          }
        }

        // Don't auto-deploy locally in case of nested execution.
        if (ldr instanceof GridDeploymentClassLoader) {
          return null;
        }

        try {
          // Check that class can be loaded.
          cls = ldr.loadClass(meta.alias());

          spi.register(ldr, cls);

          rsrc = spi.findResource(alias);

          if (rsrc != null && rsrc.getResourceClass().equals(cls)) {
            if (log.isDebugEnabled()) {
              log.debug("Retrieved auto-loaded resource from spi: " + rsrc);
            }

            dep = deploy(ctx.config().getDeploymentMode(), ldr, cls, alias);

            if (dep == null) {
              return null;
            }
          } else {
            U.warn(
                log,
                "Failed to find resource from deployment SPI even after registering it: "
                    + meta.alias());

            return null;
          }
        } catch (ClassNotFoundException e) {
          if (log.isDebugEnabled()) {
            log.debug(
                "Failed to load class for local auto-deployment [ldr="
                    + ldr
                    + ", meta="
                    + meta
                    + ']');
          }

          return null;
        } catch (GridSpiException e) {
          U.error(log, "Failed to deploy local class: " + meta.alias(), e);

          return null;
        }
      }
    }

    if (cls != null) {
      recordDeploy(cls, alias, meta.isRecord());

      dep.addDeployedClass(cls, meta.className(), meta.alias());
    }

    if (log.isDebugEnabled()) {
      log.debug("Acquired deployment class: " + dep);
    }

    return dep;
  }
  /** {@inheritDoc} */
  @Override
  public GridDeployment getDeployment(GridDeploymentMetadata meta) {
    assert meta != null;

    assert ctx.config().isPeerClassLoadingEnabled();

    // Validate metadata.
    assert meta.classLoaderId() != null;
    assert meta.senderNodeId() != null;
    assert meta.sequenceNumber() >= -1;
    assert meta.parentLoader() == null;

    if (log.isDebugEnabled())
      log.debug("Starting to peer-load class based on deployment metadata: " + meta);

    while (true) {
      List<SharedDeployment> depsToCheck = null;

      SharedDeployment dep = null;

      synchronized (mux) {
        // Check obsolete request.
        if (isDeadClassLoader(meta)) return null;

        List<SharedDeployment> deps = cache.get(meta.userVersion());

        if (deps != null) {
          assert !deps.isEmpty();

          for (SharedDeployment d : deps) {
            if (d.hasParticipant(meta.senderNodeId(), meta.classLoaderId())
                || meta.senderNodeId().equals(ctx.localNodeId())) {
              // Done.
              dep = d;

              break;
            }
          }

          if (dep == null) {
            GridTuple2<Boolean, SharedDeployment> redeployCheck = checkRedeploy(meta);

            if (!redeployCheck.get1()) {
              // Checking for redeployment encountered invalid state.
              if (log.isDebugEnabled())
                log.debug("Checking for redeployment encountered invalid state: " + meta);

              return null;
            }

            dep = redeployCheck.get2();

            if (dep == null) {
              // Find existing deployments that need to be checked
              // whether they should be reused for this request.
              for (SharedDeployment d : deps) {
                if (!d.isPendingUndeploy() && !d.isUndeployed()) {
                  if (depsToCheck == null) depsToCheck = new LinkedList<SharedDeployment>();

                  if (log.isDebugEnabled()) log.debug("Adding deployment to check: " + d);

                  depsToCheck.add(d);
                }
              }

              // If no deployment can be reused, create a new one.
              if (depsToCheck == null) {
                dep = createNewDeployment(meta, false);

                deps.add(dep);
              }
            }
          }
        } else {
          GridTuple2<Boolean, SharedDeployment> redeployCheck = checkRedeploy(meta);

          if (!redeployCheck.get1()) {
            // Checking for redeployment encountered invalid state.
            if (log.isDebugEnabled())
              log.debug("Checking for redeployment encountered invalid state: " + meta);

            return null;
          }

          dep = redeployCheck.get2();

          if (dep == null)
            // Create peer class loader.
            dep = createNewDeployment(meta, true);
        }
      }

      if (dep != null) {
        if (log.isDebugEnabled())
          log.debug("Found SHARED or CONTINUOUS deployment after first check: " + dep);

        // Cache the deployed class.
        Class<?> cls = dep.deployedClass(meta.className(), meta.alias());

        if (cls == null) {
          U.warn(
              log,
              "Failed to load peer class (ignore if class got undeployed during preloading) [alias="
                  + meta.alias()
                  + ", dep="
                  + dep
                  + ']');

          return null;
        }

        return dep;
      }

      assert meta.parentLoader() == null;
      assert depsToCheck != null;
      assert !depsToCheck.isEmpty();

      /*
       * Logic below must be performed outside of synchronization
       * because it involves network calls.
       */

      // Check if class can be loaded from existing nodes.
      // In most cases this loop will find something.
      for (SharedDeployment d : depsToCheck) {
        // Load class. Note, that remote node will not load this class.
        // The class will only be loaded on this node.
        Class<?> cls = d.deployedClass(meta.className(), meta.alias());

        if (cls != null) {
          synchronized (mux) {
            if (!d.isUndeployed() && !d.isPendingUndeploy()) {
              if (!addParticipant(d, meta)) return null;

              if (log.isDebugEnabled())
                log.debug(
                    "Acquired deployment after verifying it's availability on "
                        + "existing nodes [depCls="
                        + cls
                        + ", dep="
                        + d
                        + ", meta="
                        + meta
                        + ']');

              return d;
            }
          }
        } else if (log.isDebugEnabled()) {
          log.debug(
              "Deployment cannot be reused (class does not exist on participating nodes) [dep="
                  + d
                  + ", meta="
                  + meta
                  + ']');
        }
      }

      // We are here either because all participant nodes failed
      // or the class indeed should have a separate deployment.
      for (SharedDeployment d : depsToCheck) {
        // Temporary class loader.
        ClassLoader temp =
            new GridDeploymentClassLoader(
                GridUuid.randomUuid(),
                meta.userVersion(),
                meta.deploymentMode(),
                true,
                ctx,
                ctxLdr,
                meta.classLoaderId(),
                meta.senderNodeId(),
                meta.sequenceNumber(),
                comm,
                ctx.config().getNetworkTimeout(),
                log,
                ctx.config().getPeerClassLoadingClassPathExclude(),
                0,
                false);

        String path = U.classNameToResourceName(d.sampleClassName());

        // We check if any random class from existing deployment can be
        // loaded from sender node. If it can, then we reuse existing
        // deployment.
        InputStream rsrcIn = temp.getResourceAsStream(path);

        if (rsrcIn != null) {
          // We don't need the actual stream.
          U.closeQuiet(rsrcIn);

          synchronized (mux) {
            if (d.isUndeployed() || d.isPendingUndeploy()) continue;

            // Add new node prior to loading the class, so we attempt
            // to load the class from the latest node.
            if (!addParticipant(d, meta)) {
              if (log.isDebugEnabled())
                log.debug(
                    "Failed to add participant to deployment "
                        + "[meta="
                        + meta
                        + ", dep="
                        + dep
                        + ']');

              return null;
            }
          }

          Class<?> depCls = d.deployedClass(meta.className(), meta.alias());

          if (depCls == null) {
            U.error(
                log,
                "Failed to peer load class after loading it as a resource [alias="
                    + meta.alias()
                    + ", dep="
                    + dep
                    + ']');

            return null;
          }

          if (log.isDebugEnabled())
            log.debug(
                "Acquired deployment class after verifying other class "
                    + "availability on sender node [depCls="
                    + depCls
                    + ", rndCls="
                    + d.sampleClass()
                    + ", sampleClsName="
                    + d.sampleClassName()
                    + ", meta="
                    + meta
                    + ']');

          return d;
        } else if (log.isDebugEnabled())
          log.debug(
              "Deployment cannot be reused (random class could not be loaded from sender node) [dep="
                  + d
                  + ", meta="
                  + meta
                  + ']');
      }

      synchronized (mux) {
        if (log.isDebugEnabled())
          log.debug(
              "None of the existing class-loaders fit (will try to create a new one): " + meta);

        // Check obsolete request.
        if (isDeadClassLoader(meta)) return null;

        // Check that deployment picture has not changed.
        List<SharedDeployment> deps = cache.get(meta.userVersion());

        if (deps != null) {
          assert !deps.isEmpty();

          boolean retry = false;

          for (SharedDeployment d : deps) {
            // Double check if sender was already added.
            if (d.hasParticipant(meta.senderNodeId(), meta.classLoaderId())) {
              dep = d;

              retry = false;

              break;
            }

            // New deployment was added while outside of synchronization.
            // Need to recheck it again.
            if (!d.isPendingUndeploy() && !d.isUndeployed() && !depsToCheck.contains(d))
              retry = true;
          }

          if (retry) {
            if (log.isDebugEnabled()) log.debug("Retrying due to concurrency issues: " + meta);

            // Outer while loop.
            continue;
          }

          if (dep == null) {
            // No new deployments were added, so we can safely add ours.
            dep = createNewDeployment(meta, false);

            deps.add(dep);

            if (log.isDebugEnabled())
              log.debug(
                  "Adding new deployment within second check [dep=" + dep + ", meta=" + meta + ']');
          }
        } else {
          dep = createNewDeployment(meta, true);

          if (log.isDebugEnabled())
            log.debug(
                "Created new deployment within second check [dep=" + dep + ", meta=" + meta + ']');
        }
      }

      if (dep != null) {
        // Cache the deployed class.
        Class<?> cls = dep.deployedClass(meta.className(), meta.alias());

        if (cls == null) {
          U.warn(
              log,
              "Failed to load peer class (ignore if class got undeployed during preloading) [alias="
                  + meta.alias()
                  + ", dep="
                  + dep
                  + ']');

          return null;
        }
      }

      return dep;
    }
  }