TF_Status* status) {
  absl::MutexLock lock(&mu_);
  if (block->timestamp == 0) {
    // The block was evicted from another thread. Allow it to remain evicted.
    return TF_SetStatus(status, TF_OK, "");
  }
  if (block->lru_iterator != lru_list_.begin()) {
    lru_list_.erase(block->lru_iterator);
    lru_list_.push_front(key);
    block->lru_iterator = lru_list_.begin();

  //
  // Validation requirements:
  //  1. certificate must contain one or more PEM blocks.
  //  2. All PEM blocks must have the "CERTIFICATE" label, contain no headers, and the encoded data
  //   must be a BER-encoded ASN.1 Certificate structure as described in section 4 of RFC5280.
  //  3. Non-PEM content may appear before or after the "CERTIFICATE" PEM blocks and is unvalidated,

package ssa

import (
	"cmd/internal/src"
	"fmt"
)

// Block represents a basic block in the control flow graph of a function.
type Block struct {
	// A unique identifier for the block. The system will attempt to allocate
	// these IDs densely, but no guarantees.
	ID ID

	// Source position for block's control operation
	Pos src.XPos

	// The kind of block this is.
	Kind BlockKind

	// Likely direction for branches.

    private final List<TestParticipant> participants
    private final Lock lock

    CompositeTestParticipant(ConcurrentTestUtil owner, Lock lock, List<TestParticipant> participants) {
        super(owner)
        this.participants = participants
        this.lock = lock
    }

    void running() {
        lock.lock()
        try {
            participants*.running()
        } finally {

	if len(pemData) == 0 {
		return nil
	}

	blocks := 0
	for {
		block, remainingData := pem.Decode(pemData)
		if block == nil {
			break
		}

		if block.Type != utilcert.CertificateBlockType {
			return fmt.Errorf("only CERTIFICATE PEM blocks are allowed, found %q", block.Type)
		}
		if len(block.Headers) != 0 {
			return fmt.Errorf("no PEM block headers are permitted")
		}
		blocks++

  //
  // Validation requirements:
  //  1. certificate must contain one or more PEM blocks.
  //  2. All PEM blocks must have the "CERTIFICATE" label, contain no headers, and the encoded data
  //   must be a BER-encoded ASN.1 Certificate structure as described in section 4 of RFC5280.
  //  3. Non-PEM content may appear before or after the "CERTIFICATE" PEM blocks and is unvalidated,

}

type label struct {
	parent *block       // block containing this label declaration
	lstmt  *LabeledStmt // statement declaring the label
	used   bool         // whether the label is used or not
}

type block struct {
	parent *block       // immediately enclosing block, or nil
	start  Pos          // start of block
	lstmt  *LabeledStmt // labeled statement associated with this block, or nil
}

  }) {n = 2 : i32, operandSegmentSizes = array<i32: 0, 0>} : () -> ()
  func.return
}

// -----

// Check that an empty replicate block is invalid.
func.func @verifier_replicate_empty_block() {
  "tf_device.replicate" () ({
// expected-error@-1 {{'tf_device.replicate' op expects a non-empty block}}
  ^entry:

	//
	// Validation requirements:
	//  1. certificate must contain one or more PEM blocks.
	//  2. All PEM blocks must have the "CERTIFICATE" label, contain no headers, and the encoded data
	//   must be a BER-encoded ASN.1 Certificate structure as described in section 4 of RFC5280.
	//  3. Non-PEM content may appear before or after the "CERTIFICATE" PEM blocks and is unvalidated,
	//   to allow for explanatory text as described in section 5.2 of RFC7468.

import java.util.concurrent.CopyOnWriteArraySet;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

/**
 * <p>A rule for testing concurrent code.</p>
 *